&EFA
United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA-600/S2-82-077 Feb. 1983
Project Summary
Optimizing Salinity Control
Strategies for the Upper
Colorado River Basin
Robert G. Evans, Wynn R. Walker, and Gaylord V. Skogerboe
Salinity is the most serious water
quality problem in the Colorado River
Basin. Its impact, felt largely in the
Lower Basin, is acute because that
basin is approaching conditions of full
development and utilization of all
available water resources. Current
estimates indicate that each mg/l-
increase in salinity concentration at
Imperial .Dam results in $450,000
annual damages. To offset salinity
caused by development of the basin's
vast energy supplies, and to allow the
seven Colorado River Basin states to
fully utilize their allocation of Colorado
River water, it is necessary to formu-
late cost-effective salinity control
strategies for the basin.
A simple multi-level nonlinear opti-
mization procedure was utilized to
formulate the most cost-effective
array of salinity control strategies for
the Upper Colorado River Basin. The
incremental cost-effectiveness meth-
odology qualitatively indicates the
location and type of alternatives to be
implemented in a least-cost basin-
wide salinity control program. The
results also qualitatively indicate the
anticipated salt load reduction and
anticipated annual costs of each
increment of salinity reduction for any
preselected level of control. The
analysis was limited to projects
designated in PL 93-320 (Colorado
River Basin Salinity Control Act, June
24, 1974). Costs and salinity contri-
butions associated with various alter-
natives were generated using January.
1980 estimated conditions.
Cost-effectiveness functions were
developed for each of the major canals
and laterals, the aggregate laterals
under each canal, and an array of on-
farm improvements for each agri-
cultural project area. Similarfunctions
also were developed for point sources
such as Paradox Valley, Glenwood-
Dotsero Springs and Crystal Geyser.
Collection and desalination of agricul-
tural return flows were also considered.
Marginal cost analysis based on
current damage estimates indicates
that the optimal cost-effective salinity
control program in the Upper Basin
would cost about $30 million annually
and remove about 1.2 million mega-
grams of salt per year (one megagram
is equal to one metric ton). In addition,
it was concluded that maintenance of
the 1972 salinity concentration levels
at Imperial Dam cannot be cost-
effectively achieved and perhaps
should be allowed to rise over the
1972 figure by as much as 180 mg/l.
Optimal salinity control programs
are presented for the individual alter-
natives, for individual areas or projects.
for the states of Colorado, Utah and
Wyoming, as well as for the Upper
Colorado River Basin. Sensitivity
analysis showed that very large errors
in costs and component salt loading
would have to be evident to change
the optimal salinity control strategy.
This Project Summary was devel-
oped by EPA's Roberts. Kerr Environ-
mental Research Laboratory, Ada.
OK, to announce key findings of the
research project that is fully docu-
-------
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The primary water quality problem in
the Colorado River Basin is salinity. This
problem tends to be so dominant that it
overshadows most other water quality
considerations. Fortunately, the salt
pollution of the Colorado River by either
man-made or natural depletions and/or
discharges is not a general health
hazard. Salinity is basically an economic
problem in which a progressive build-up
in concentration toward the lower
reaches causes a reduction of the
water's utility to urban and agricultural
users. The annual total salt burden is
about 10 million megagrams (Mgm).
Concentrations of salinity in the
Colorado River range from less than
50 mg/l in the high mountain head-
waters to more than 850 mg/l at
Imperial Dam. Further deterioration of
Colorado River quality is expected as a
result of both water and energy resource
development. This deterioration will
occur even if salinity reduction measures
are instituted, although it would then
occur at a slower rate. If no salinity
control measures are developed, salinity
increases at Imperial Dam will range
from 1,150 mg/l to 1,340 mg/l by the
year 2000.
To date, all salinity control planning
has been oriented toward reducing the
salt load of the Colorado River; the
economics of control have not been of
overriding concern. Development of
cost-effective programs, or design of
construction projects with benefit-cost
ratios greater than one, has not had a
high priority; although control costs
have been compared to estimated
annual damages at Imperial Dam. The
argument presented in favor of the non-
economic approach is that Congress (PL
93-320) mandated certain projects
(Figure 1) and that these projects would
include specific construction items such
as canal linings. However, since that
legislation was passed, the results of
numerous investigations have become
available which permit the formulation
of cost-effective salinity control projects.
The purpose of Public Law 93-320
was to mitigate salinity increases
caused by the individual Colorado River
Basin states in developing their respec-
tive allowances of water from the
Colorado River. Title II of PL 93-320
(Section 207) specifically states that
"nothing in this title shall be construed
to alter, amend, repeal, modify, inter-
pret, or be in conflict with the provi-
sions of the Colorado River Compact (45
Stat., 1957), the Upper Colorado River
Basin Compact (63 Stat., 31).. ./'orany
other compact or agreement and/or any
project which allocates the Colorado
River as to quantity.
PL 93-320, Title II directs the Secre-
tary of the Interior to investigate, plan
and implement a salinity control program
in the Upper Colorado River Basin. The
legislation specifically names several
projects for construction and further
study. The projects in the Upper Colorado
River Basin are summarized in Table 1.
According to a U.S. Government
Accounting Office (GAO) Report in
1979, it is doubtful that the Salinity
Control Program as defined in PL 93-
320 will reduce the salt in the Colorado
River as much as predicted. Further-
more, at least six of the seventeen
projects are questionable economically.
For example. Crystal Geyser and Las
Vegas Wash, as formulated, have very
* Authorized Water Development Projects1
A Authorized for Construction Water Quality
Improvement Project, Title II
A Water Quality Improvement Project \ {Wyoming
Under Investigation, Title II i
Water Quality Improvement Project, '
•"-^ Transmountain Diversions
'Does not include developments existing
Prior to Authorization of Colorado River
Storage Project
PUEBLO. DENVER
AURORA AND
iRAOOSPGS
IESTAKE
RYINOPAN
ARKANSAS
I DEPENDENCE PASS
Nevada
SOUTMERI
NEVADA WATE1
50 0
Scale
100 200 250 kilometers
United States
Mexico
Figure 1. The Colorado River Basin and salinity control projects designated by PL
93-320.
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high costs and will have a "minor
impact in reducing the river's salinity..."
However, the GAO analysis only exam-
ined the projects in aggregate as
formulated by the U.S. Department of
the Interior, and did not address the fact
that individual components of a salinity
control project may indeed be very cost-
effective while a total program may not
be economically viable. They did not
consider that perhaps only selected
portions of various salinity control
projects should be constructed, which
research has shown to be the case.
The primary questions left unan-
swered by PL 93-320 are the extent of
salinity control programs construction
and the degree of effort to be expended
in pursuit of the goals of this legislation.
For example, without regard to benefits
and costs, the Water and Power Re-
sources Service (WPRS) presents data
illustrated in Figure 2 that indicate the
difficulty of maintaining the mandated
1972 salinity levels at Imperial Dam.
Preliminary analyses have clearly
shown that several of the projects noted
in PL 93-320 have benefit-cost ratios
much less than one, based on annual
damages of $450,000 per mg/l in-
crease at Imperial Dam.
Aggregate Salinity Control
Programs
To date, analyses have not been made
of salinity control projects in which the
most cost-effective strategies and
alternatives for implementation in an
areawide or basin-wide program were
identified. The preceding discussion
illustrated the areawide approach, and
the following discussion demonstrates
the next optimized level of the analysis,
which is a basin-wide cost-effective
salinity control program.
The most cost-effective salinity
control program for the Upper Colorado
River Basin is presented in Figures 3
and 4. Figure 3 lists the results of this
basin-wide level of optimized salinity
control by alternative, and Figure 4
indicates the individual state projects
included in PL 93-320. Figure 3 shows,
on-farm improvements and lateral
lining constitute the largest portion of
the program. The state of Colorado
contains the largest and the most
designated salinity control projects, as
seen in Figure 4.
If each state was required to control
its own salinity increases, only Colorado
and Utah could do so in a cost-effective
manner. It is doubtful if Wyoming could
reduce the salinity by, at most, another
25 mg/l from the Blacks Fork and other
irrigated areas. Therefore, Wyoming
would probably have to resort to large-
scale desalination of the river and/or
the point sources to achieve its goal.
This would be extremely expensive with
a downstream damage reduction/cost
ratio much less than one.
New Mexico is actually expected to
overdraw its Colorado River water
allocation by 1985. However, agricul-
tural salinity control, or a large scale
collector-desalination system, would be
very costly to implement for widely
dispersed areas with relatively low
salinity contributions.
Figure 5 presents the optimal cost-
effective basin-wide salinity control
alternatives plotted under the Water
and Power Resources Service forecast
Table 1. Summary of Salt Loading Attributed to the Various Sources and the
Estimated Attainable Salinity Control Levels for Total Programs of
Projects Designated by PL 93-320 in the Upper Colorado River Basin
Estimated
Salt Load mg/l
Reduction Reduction
Mgm at Imperial Dam
Source
Total Salt
Load Contribution
Mgm
AGRICULTURAL CONTROL PROJECTS
Grand Valley 630,000
Lower Gunnison 800,000
Uncompahgre Valley 350,000
Uintah Basin 395,000
Price -San Rafael Drainage 210,000
Dirty De vil River 52,000
McElmo Creek 85,000
Big Sandy River 125,000
POINT SOURCE CONTROL PROJECTS
Paradox Valley 180,000
Glenwood-Dotsero Springs 400,000
Meeker Dome 29,500
Crystal Geyser 2,720
372,000
570,000
220,000'
182.000
50,000
24,000
50,000
81,000
163,000
214,300
29,500
2,720
43
65
25.3
21
7.3
2.8
6.0
9.3
18.7
25.0
3.4
0.3
202.90
'Canal and Lateral Lining Only (USDI, WPRS. 1980c).
^1300r
| 120°
Q
•2
I//00
CQ
X
7000
300
I
800-
700
Curve A
____
1 9 72 Salinity Standard at
Imperial Dam
43 Development Projects
without Salinity Control
Curve A + 4 Authorized
Salinity Control Projects
(Reduction of 575,300
Mgm)
Curve B+13 Salinity Con-
trol Projects under Study
(Reduction of 1,710.000
Mgm)
(Need Reduction of
2,570,000 Mgm)
1980
2000
2000+
Figure 2.
1990
Year
Salinity increase at Imperial Dam projected by the Water and Power
Resources Service (USDI, BR, 1979d).
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curve of salinity increase at Imperial
Dam. As can be seen, almost all of the
salinity control projects except agricul-
tural desalination should be imple-
mented by 1985. Fortunately, the
salinity increases have not followed this
curve and are presently at a somewhat
lower level than the 879 mg/l annual
average which occurred-in 1972. This
has been due partially to delayed
construction of projects, delayed energy
resources development, and some
relatively high runoff years. The 1980
average annual value is estimated to be
802 mg/l. However, present indications
are that the projected rapid increases
have been offset at most by about 10
years, and that all of the cost-effective
projects should be on-line at the latest
by 1995. In other words, it is expected
that the salinity concentration at
Imperial Dam will again reach the 1972
levels by 1985.
If the January, 1980 damage cost of
$450,000/mg/l at Imperial Dam is
accepted as a true cost, then it is
possible to assess the damage costs of
increased salinity concentrations due to
delaying construction of the salinity
control program. For example, using the
1985 salinity levels from Figure 5(210
mg/l increase) for comparison, and if
only one-fourth of the necessary salinity
control is constructed at that time, then
the annual costs of the delay are about
$71 million. Correspondingly, if only
one-third is complete, the delay cost is
about $63.3 million annually. This also
assumes that the 1972 level of 879
mg/l should be maintained.
Conclusions
1. The conceptual model, simple
nonlinear optimization and the
resulting array of cost-effective
salinity control strategies for the
Upper Basin represent and illus-
trate the use of an easily used
environmental quality planning
tool.
2. Cost-effective salinity control
strategies to compensate for new
resource development or water
transfers into or out of the basin
which affect salinity can be easily
developed and evaluated.
3. As new data become available or
changes in political attitudes or
directives may dictate, the opti-
mal salinity control strategies
can be easily and continually
updated and re-evaluated.
4. The methodology and results
indicate with a fair degree of
O
Q
I
100
90
80
70
60
50
40
30-i-
20
10
0
5
I
I
I
c
o
1
11
.5 ^J
CO
-J
$45O.^pg/jrig/l_atJmperial D,
\/ Glenwood Dotsero Springs
Paradox By-Pass
Canal Lining
Sublette Flats, Wyoming-*
Lateral Linings
On-Farm Improvements
1200
1600
-t-
2000
2400 2800
Salt Load Reduction, Mgm x 10-3
Figure 3. Optimal Upper Colorado River Basin salinity control by alternatives.
110r
400
800 1200 1600 2000
Salt Load Reduction, Mgm x 10-3
2400 2800
Figure 4. Optimal Upper Colorado River Basin salinity control program delineated
by state.
4
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1200
I
•2
I"00
I
e/ooo
Q
300
WPFtS Forecast
Curve A \
Desalination
Canal Linings •
Glenwood Dotsero Springs
Paradox By-Pass
Lateral Linings
^•Sublette Flats.
Wyoming
On-Farm Improvements
879 mg/l
1972 1975
1980
1985
Year
1990
1995
2000
Figure 5. Cost-effective implementation strategy for optimal level of salinity
control alternatives in the Upper Colorado River Basin.
certainty the priority and magni-
tude of control for each alter-
native, for each area, and for the
basin-wide PL 93-320 salinity
control program.
5. Some degree of on-farm improve-
ments and lateral linings are
cost-effective in every agricul-
tural area examined in the Upper
Basin. However, this work must
be accompanied by greatly in-
creased technical assistance to
the growers by the implementing
agency and/or extension per-
sonnel. These programs are the
most cost-effective, and better
information and/or data are not
likely to affect their implemen-
tation as a salinity control mea-
sure.
6. All lining of the laterals and 58
percent of the on-farm improve-
ments (cutback irrigation) in the
Grand Valley should be construc-
ted before lining any of the
Government Highline Canal. In
fact, some on-farm and lateral
linings should be done in all
agricultural areas before canal
lining is initiated.
7. At current damage estimates of
$450,0007mg/l at Imperial Dam,
only about 57 percent of the
canals in the Grand Valley should
be lined. The Grand Valley has
the most canals to be lined of any
area at this level of damages.
8. Most of the on-farm, lateral
lining, and the very small canal
(actually smaller than many
laterals) lining salinity control
program should be constructed
in the Lower Gunnison area
before canal linings are initiated.
9. Programs in the Uintah Basin,
Price-San Rafael Rivers, Muddy
Creeks, and McElmo Creek will
basically consist of on-farm and
lateral linings with very little
canal lining.
10. The use of canals for winter
livestock water causes substan-
tial salt loading from several
areas in the basin and contri-
butes numerous problems of
local waterlogging and soil sali-
nation.
11. The barrier well network and
Sublette Flat evaporation area as
proposed by the USDA, Soil
Conservation Service, and mini-
mal on-farm improvements are
the most cost-effective salinity
program for the Big Sandy area in
Wyoming. The "buy-out" alter-
native as proposed by some local
landowners was evaluated and
found not cost-effective.
12. Collection and reverse osmosis
desalination of agricultural return
flows should be included as a
viable salinity control alternative
in all irrigated areas. However, at
current estimates of downstream
damages, desalination would not
be implemented.
13. The by-pass alternative for the
Paradox Valley was evaluated
and found to be more cost-
effective than the proposed Radi-
um evaporation pond alternative.
This was primarily due to the
greatly increased costs of evapo-
ration ponds.
14. The proposed desalination of the
Glenwood-Dotsero Springs in
Colorado was evaluated in detail
as part of this study. It was
concluded that the most econom-
ical alternative was a primary
reverse osmosis plant followed
by a much smaller secondary
multi-stage flash distillation unit.
However, at current average
damage estimates, this project is
marginally feasible.
15. The use of average costs per
mg/l of treatment is misleading
and should not be used in the
delineation or phasing of salinity
control projects.
16. At current average damage esti-
mates, it is cost-effective to treat
only about 48 to 50 percent of the
total attainable salt load reduc-
tion from the projects designated
in PL 93-320.
17. All of this analysis points to the
fact that the arbitrary target of
maintaining 1972 salinity levels
at Imperial Dam cannot be cost-
effectively attained. In fact, these
results indicate that the target
level should be increased to
about 1,030 or 1,040 mg/l or
more.
18. Present trends indicate that all
of the cost-effective salinity
control programs should be on-
line no later than 1995. The
increased damage costs due to
delayed construction of these
projects can be substantial.
19. Sensitivity analysis of the data
and the optimization procedure
indicate that substantial error in
costs and the respective salt load
contributions of the individual
alternatives would have to occur
to change the optimal order of
implementation of a basin-wide
salinity control program.
Recommendations
1. Desired levels of salinity control
must be determined and imple-
mented as soon as possible since
they will dictate the type and
extent of many of the alterna-
tives. This is especially true for
on-farm improvements.
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2. Because on-farm improvements
and lateral linings are cost-
effective in all of the irrigated
areas examined in this analysis,
the list of areas included in PL
93-320 should be expanded.
These basic on-farm improve-
ments should be implemented in
all of the agricultural areas as the
initial most cost-effective salinity
control program.
3. The Soil Conservation Service,
the Extension Service and the
other technical agencies involved
in salinity control should make a
long-term commitment of ade-
quate technical assistance to the
growers. The on-going work
in the Grand Valley clearly indi-
cates the need for this type of
program. Recruiting and training
personnel for this type of activity
will be necessary.
4. On-farm improvement and lateral
lining programs consistent with
selected levels of basin-wide
salinity control should be started
as soon as possible in all of the
irrigated areas.
5. The Sublette Flats evaporation
area and a network of barrier
wells and a minimal on-farm
improvement program should be
initiated as the total salinity
control program for the Big
Sandy area in Wyoming.
6. The use of canals and laterals for
winter livestock water should be
eliminated, if dependable alter-
native water supplies such as
rural water districts or ground-
water could be developed.
7. Design and construction of the
by-pass alternative for the Para-
dox Valley salt source should
begin as soon as possible. In
addition, it may be necessary to
construct a series of small wells
to intercept some of the ground-
water inflow to the salt dome-
brine interface.
8. A salinity damage function is
presently being developed under
contract to the Water and Power
Resources Service. When this
information becomes available,
the feasibility of maintaining the
1972 salinity concentration levels
at Imperial Dam should be re-
evaluated.
9. Results of this analysis indicate
the advisability of implementing
the identified most cost-effective
salinity control program regard-
less of where or which state the
salinity increases occurred. Colo-
rado will contain the major
programs, and these projects will
serve to counterbalance salinity
increases in other areas, Physi-
cally, Wyoming would not be able
to control its own salinity in-
creases.
10. The scope of the LowerGunnison
project should be expanded by
the Water and Power Resources
Service to include all of the
irrigated lands in the area, and
not be restricted to only the
Uncompahgre Project lands. The
canal and lateral lining program
proposed by the WPRS is not
cost-effective and should be re-
evaluated. The possibilities for
gravity-powered sprinkler sys-
tems and closed conduit canal
and lateral linings in the North
Fork of the Gunnison River should
be examined.
11. There is a definite need to obtain
a better data base for several of
the areas, especially McElmo
Creek in southwestern Colorado.
The groundwater base flows in
the Lower Gunnison, McElmo
Creek and the Uintah Basin
require further effort. Seepage
rate data for canals and laterals
in project areas are lacking.
These data should be collected to
define the most cost-effective
incremental canal and lateral
lining programs for each area.
12. Studies should be initiated in the
Price-San Rafael, Uintah, McElmo
and Lower Gunnison areas to
determine the relative magni-
tude of the natural salt contri-
bution for each irrigated area.
This information would be nec-
essary to delineate the more
exact cost-effectiveness func-
tions prior to undertaking a
construction program.
Robert G. Evans is with Washington State University, Prosser, WA 99350; Wynn
R. Walker is with Utah State University, Logan, UT 84322; and Gaylord V.
Skogerboe is with Colorado State University, Fort Collins, CO 80523.
James P. Law, Jr., is the EPA Project Officer (see below).
The complete report, entitled "Optimizing Salinity Control Strategies for the Upper
Colorado River Basin," (Order No. PB 83-136 143; Cost: $19.00, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
P.O. Box 1198
Ada, OK 74820
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United States
Environmental Protection
Agency
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Information
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