EPA R2-72-047
October 1972 Environmental Protection Technology Series
Evaluation of Canal Lining
for Salinity Control
in Grand Valley
Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agencyf have
been grouped into five series. These five bread
categories were"established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
U. Environmental Monitoring
5. Soci©economic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This v^ork provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
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EPA-R2-72-0^7
October 1972
EVALUATION OF CANAL LINING FOR
SALINITY CONTROL IN GRAND VALLET
By
Gaylord V. Skogerboe
Wynn R. Walker
Contract No. 1^-01-201
Project 13030 DOA
Project Officer
Dr. James P. Law, Jr.
Robt. S. Kerr Water Res. Center, EPA
P. 0. Box 1198
Ada, Oklahoma 7^820
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C.
For sate by the Superintendent of Documents, U.S. Government Printing Office
Washington. D.C. 20402-Price $2.75
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EPA Review Notice
This report has been reviewed by the Office
of Research and Monitoring, EPA, and
approved for publication. Approval does
not signify that the contents necessarily
reflect the views and policies of the
Environmental Protection Agency, nor does
mention of trade names or commercial prod-
ucts constitute endorsement or recommend-
ation for use.
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ABSTRACT
Introduction of seepage and deep percolation losses to the
saline soils and aquifers, and the eventual return of these
flows to the river system with their large salt loads, make
the Grand Valley in Colorado one of the more significant
salinity sources in the Upper Colorado River Basin. The
Grand Valley Salinity Control Demonstration Project was
designed to evaluate the salinity control effectiveness of
canal and lateral linings for reduction of seepage losses
into the ground water.
In order to meet the specific objectives of this study, a
detailed evaluation of the necessary hydrologic and salin-
ity parameters in the principal demonstration area was made.
A hydro-salinity model has been prepared, which has allowed
the itemizing of the various segments of the dual flow sys-
tem into water and salt budgets for the periods prior to
and immediately after the construction of the linings. In
addition, the results of this study and others conducted
previously were employed to derive some generalized valley-
wide water and salt budgets.
Conclusions and recommendations formulated during the course
of the study, which were deemed pertinent in the study area,
were extended to a valley wide context. Suggestions made
have been based upon the results obtained in this study con-
cerning areas of needed research for more effective future
salinity control, institutional constraints which must be
examined for efficient salinity management, and improvements
to the existing agricultural system in Grand Valley that will
reduce salt loadings to the Colorado River from the valley.
111
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CONTENTS
Section Page
I Conclusions 1
II Recommendations 3
III Introduction 5
IV The Grand Valley Area 15
V Summary of Previous Research 43
VI Grand Valley Hydro-Salinity System 59
VII Field Investigations Methodology 77
VIII Water Quality Characteristics of the
Grand Valley 97
IX Evaluations of the Conveyance System 115
X Evaluations of the Farm Irrigation System 135
XI Evaluations of the Ground Water System 157
XII Water and Salt Budgets 165
XIII Salinity Management Alternatives 181
XIV Acknowledgments 191
XV References 193
XVI Publications 199
v
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FIGURES
Page
1 The Colorado River Basin 6
2 Relative Magnitude of Salt Sources in the Colo-
rado River Basin 7
3 The Grand Valley, Colorado 9
4 Relative Magnitude of Agricultural Salt Sources
in the Colorado River Basin 10
5 Intensive Study Area, Area I, of the Grand
Valley Project 12
6 General Geologic Cross-Section of the Grand
Valley 32
7 Soil Classification Map of Intensive Study
Area, Area I 34
8 Cross-Sections of Soil Profiles in Area I 37
9 Normal Precipitation and Temperature at Grand
Junction, Colorado 41
10 Construction and Driller's Log at 1951 Test Well
for Pump Drainage 47
11 Water and Salt Flow Diagram in the Grand Valley
Based on 1914-157 Data Adjusted to 1957 Condi-
tions 55
12 Schematic Water and Salt Budget for the Grand
Valley During 1963-64 Water Years 57
13 Schematic Diagram of Generalized Hydro-Salinity
Model 61
vi
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FIGURES (Continued)
Page
14 Illustrative Flow Chart of Root Zone Budgeting
Procedure 69
15 Illustrative Flow Chart of Ground Water Modeling
Procedure 71
16 Schematic Flow Chart of Hydro-Salinity Model 74
17 Location of Instrumentation in Area I 78
18 Project Personnel Using the Jetting Technique to
Install Pipe Piezometers 80
19 One-Foot Cutthroat Flume Located in an Open
Drain in the Test Area 83
20 Typical Lateral Turnout Structure Used in the
Grand Valley 85
21 Typical Discharge Relationship for a Lateral
Turnout Rated in the Test Area 85
22 Canal Seepage Measurement Using the Ponding
Method 8 8
23 Lateral System Supplied by the Stub Ditch, Price
Ditch, and Government Highline Canal in Area I 89
24 Lateral System Supplied by the Grand Valley Canal
in Area I 9°
25 Lateral System Supplied by the Mesa County Ditch
in Area I 91
26 Location of Farm Efficiency Studies Conducted in
Area I 94
27 Summary of Area I Soil Sampling Data 95
28 Illustrative Diagram of the Water and Salt Flows
in the Grand Valley Area During 1970 Water Year 99
29 Diagram of Sodium Adsorption Ratios (SAR) and
Soluble Sodium Percentage (SSP) in the Grand
Valley During the 1970 Water Year 100
vn
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FIGURES (Continued)
Page
30 Diagrammatic Presentation of Cation Flows
Through the Grand Valley During 1970 Water
Year 102
31 SAR Frequency at Three USGS Stream Gaging Sta-
tions in the Grand Valley During 1970 Water
Year 103
32 Bar Graph of Constituent Analysis and Frequency
Diagram for Specific Conductance of Water
Samples from the Colorado River near Cameo,
Colorado During 1970 Water Year 105
33 Bar Graph of Constituent Analysis and Frequency
Diagram of Specific Conductance of Water Samples
from the Gunnison River near Grand Junction,
Colorado During 1970 Water Year 106
34 Bar Graph of Salt Constituents and Frequency of
Specific Conductance of Samples from the
Colorado River at Colorado-Utah State Line
During 1970 Water Year 107
35 Bar Graph of Constituents and Frequency Diagram
of Specific Conductance of Water Samples from
Drains and Washes in the Grand Valley 108
36 Bar Graph of Constituents and Frequency Diagram
of Specific Conductance of Water Samples from
the Near-Surface Groundwater in the Test Area 111
37 Frequency Diagram of SAR from Water Samples of
Near-Surface Groundwater 111
38 Bar Graph of Salt Constituents and Frequency of
Specific Conductance of Aquifer Samples in the
Test Area During Study Period 112
39 Frequency of SAR of Aquifer Samples 112
40 Grand Valley Canal Distribution System 116
41 Location within Area I of the Linings that
were Constructed
Vlll
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FIGURES (Continued)
Page
42 Slip Form Concrete Lined Section of the Stub
Ditch 124
43 Gunnite Lined Section of the Mesa County Ditch 125
44 Tile Drain Line in the Study Area 126
45 Special Purpose Structures Built as Part of
the Lining Work 127
46 Geometry and Instrumentation of the Martin Farm 137
47 Geometry and Instrumentation of the Bulla Farm 138
48 Potential Consumptive Use Rate for Corn in the
Grand Valley Area 141
49 Potential Consumptive Use Rate for Tomatoes in
the Grand Valley Area 142
50 Advance Rates of Furrow Streams on the Bulla
Farm 145
51 Advance Rates of Furrow Streams on the Martin
Farm
52 Recession Rates of Furrow Streams on the Bulla
Farm
53 Recession Rates of Furrow Streams on the Mar-
tin Farm
148
54 Specific Conductance Versus Depth Plot for the
Chemical Analysis of the Soil Moisture Sam-
ples on the Martin Farm 152
55 Specific Conductance for Various Soil Depths
During the 1971 Irrigation Season on the
Bulla Farm 153
56 Distribution of Sodium Concentration Through the
Soil Profile on the Martin Farm 154
57 Change in Sodium Concentration Through the Irri-
gation Season on the Bulla Farm 155
IX
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FIGURES (Continued)
58 Water Table Elevations, Below Surface Depths,
Average Vertical Gradients, and Cobble Pressures
for Selected Stations in the Test Area During
March 1971 160
59 Water Table Elevations, Depths Below Soil Sur-
face, Average Vertical Gradients, and Cobble
Pressure Elevation for Selected Stations in
the Test Area During July 1971 161
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TABLES
Paqe
1 Land Use Under the Grand Valley Canal System
(Including Mesa County Ditch) 17
2 Water Right Decrees for the Grand Valley Project 22
3 Land Use Under the Government Highline Canal in
1969 24
4 Land Use in the Orchard Mesa Irrigation District
During 1969 27
5 Land Use Under the Price Ditch During 1969 28
6 Land Use Under the Stub Ditch During 1969 29
7 Land Use Under the Redlands Water and Power
Company System During 1969 31
8 Soil Mapping Classification Index 35
9 Land Use Mapping Index 38
10 Land Use in Area I During 1969 39
11 Overall Seasonal Irrigation Efficiency Percent-
ages Weighted by Field Acres 50
12 Results of 1954 Infiltration Study 52
13 Results of 1952-55 Field Leaching Study Showing
Effect on Exchangeable Sodium Percentage 53
14 Results of Lateral Survey 65
15 Hydro-Salinity Model Subroutine Descriptions 75
16 Linear Regression Analysis of Specific Conduct-
ance in ymhos/cm and Total Dissolved Solids
in ppm for Colorado and Gunnison River Stations 101
17 Average Constituent Breakdown in epm for Drains
and Washes
18 Results of Ponding Tests on Canals in Area I
and II
XI
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TABLES (Continued)
Page
19 Proposed Canal Lining Construction Cost 122
20 Recommended Construction Program 123
21 Comparison of Seepage Rates Before and After
Canal Lining Using Ponding Tests 128
22 Results of Lateral Loss Investigation 133
23 Summary of the Sizes and Lengths of Laterals
Lined During the Project 134
24 Results of 1971 Farm Efficiency Investigations 143
25 Advance-Recession Analysis 150
26 Results of Hydraulic Conductivity Measurements
from Piezometers in Area I 162
27 Potential Cropland Demand in the Grand Valley
by Canal System Serving the Land 167
28 Potential Evapotranspiration Demand of the
Grand Valley 168
29 Water Budget Inflows to Area I During 1969
Study Period 171
30 Water Budget Inflows to Area I During 1971
Water Year 172
31 Salt Budget Inflows to Area I, in Tons of Total
Dissolved Solids, During the 1969 Water Year 173
32 Salt Budget Inflows to Area I, in Tons of Total
Dissolved Solids, During the 1971 Water Year 174
33 Water Budget Ground Water Flows in Area I
During the 1969 Study Period 175
34 Water Budget Ground Water Flows in Area I
During the 1971 Study Period 176
XII
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TABLES (Continued)
35 Ground Water Salt Flows in Area I, in Tons of
Total Dissolved Solids, During the 1969
Water Year 177
36 Ground Water Salt Flows in Area I, in Tons of
Total Dissolved Solids, During the 1971
Water Year 178
X1J.1
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SECTION I
CONCLUSIONS
The basis for reducing salt loadings entering the Colorado
River as it passes through the Grand Valley is to minimize
the water which is percolating through the soil profile and
into the ground water basin. At the present level of salin-
ity control technology, it is difficult to determine what
effect a 50% reduction in these flows would have. It may
vary between 30 and 70% in the corresponding reduction of
salt loadings. However, the bulk of the deep percolation
losses are the result of excessive irrigation applications
and, as such, the objective of any salinity control alterna-
tive should include measures to improve the efficiency of
on-farm water management.
The first and most important consideration in improving farm
water use is control. Implied in this realization is the
requirement of sound water measurement at the farm turnout
and again at critical division points among farmers below
the turnout. This would necessitate a considerable rehab-
ilitation of both the canal and lateral system, and the imp-
lementation of a "call period" to allow canal operators more
time for flexible water handling. In addition, it is an
important requirement that the canal companies extend their
control of the water below the canal turnout structure to
include key division points within the lateral system to
insure equitable allocation of water among users.
Another important farm water management tool that must even-
tually be considered is an irrigation scheduling program.
By simply applying the proper quantity of water at the cor-
rect time, a significant reduction in deep percolation losses
can be achieved. In this type of program, the emphasis is
not only on improving crop production by more efficient use
of water and fertilizer, but also on salinity management
which is an added dimension to the program.
Drainage in the Grand Valley is generally ineffective in at
least 30% of the lower lying areas where water table problems
become compounded by subsurface inflows from the higher lands
It has been established that the vast majority of subsurface
return flows occur in a highly permeable cobble and sand
strata resting upon the Mancos shale formation. As a result,
the possibility of employing drainage as a salinity control
program seems feasible since it would reduce the detention
time the water has contact with the highly saline soils,
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aquifer, and Mancos shale. Drainage schemes including field
tile drainage, interceptor drainage, and drainage by pumping
seem to be the most realistic methods.
It should be emphasized as an important conclusion of this
study that no single salinity control measure will effect-
ively alleviate the Grand Valley salinity problem. It is
thus essential that an integrated program of a planned com-
bination of these schemes be implemented for efficient sal-
inity control.
Probably the most binding constraint for reducing salinity
from the valley is not in the feasibility of the alternatives
mentioned above, but in the institutional structure of west-
ern water laws. In order for water management in the area
to improve without devastation of the already burdened agri-
cultural system, new mechanisms for economic incentives for
improving the efficiency of water use must be applied.
Present water laws are actually a deterrent to better water
management because any change in water use practices that
results in a water savings might cause a loss of a portion
of a water right, which is considered very valuable to an
irrigated agriculture.
The results of this study indicate that canal and lateral
lining in the test area reduced salt inflows to the Colo-
rado River by about 4700 tons annually. The bulk of this
reduction is attributable to the canal linings, but clearly
indicated is the greater importance of lateral linings.
The length of laterals, including farm head ditches, is
about ten times greater than the length of canals. The
economic benefits to the lower basin water users alone
exceed the costs ($350,000 construction plus $70,000 admin-
istration) of this project. Consequently, it seems justi-
fiable to conclude that conveyance lining in areas such as
the Grand Valley, where salt loadings reach 8 tons or more
per acre, are a feasible salinity control measure. The
local benefits accrued from reduced maintenance, improved
land value, and other factors add to the feasible nature
of conveyance linings as a salinity management alternative.
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SECTION II
RECOMMENDATIONS
Although the results of this study indicate to some degree
the effects of other salinity control practices, it is
important to realize that not enough of the technical infor-
mation concerning these alternatives to sufficiently fill
the existing gaps in present day knowledge has been pro-
vided. Therefore, certain of these practices should be
evaluated in the valley before a final salinity control plan
is formulated.
One important salinity control study that should be under-
taken is irrigation scheduling in conjunction with field
tile drainage. This type of study would not only serve to
demonstrate the effectiveness of irrigation scheduling in
reducing salinity, but also evaluate the feasibility of
field drainage for salinity control and land reclamation.
During a study such as this, considerable insight could also
be gained concerning methods to improve the basin irrigation
techniques, although further investigation may be desirable
to completely define the problem and solutions.
The most pressing need in basin technology is water quantity
and quality models capable of predicting the effects of
salinity control programs. Specifically, a model of this
nature must be capable of considering the ionic exchange and
precipitation in the soil profile. In order to accomplish
this level of modeling, additional research should be con-
ducted to evaluate the ionic movements and exchanges in the
soil moisture medium.
A valley authority representing all pertinent local inter-
ests should be formulated. This organization would serve
to promote the investigation of both physical and institu-
tional changes necessary to control salinity from Grand
Valley. In addition, it should coordinate a plan for sal-
inity control in the valley based upon an integrated scheme
of a multitude of available salinity measures.
Further, the question of allocation of the excess water
derived from more efficient management programs should be
resolved, possibly by economic incentives for abandoning,
selling, leasing, or renting the unused portion of the
water right. Because the institutional structure of present
water laws poses such an immense constraint to effective
water management, a study should be undertaken to evaluate
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possible changes in the interpretation of state water laws
to provide the necessary incentives for improved water man-
agement.
Finally, since rehabilitation of the irrigation system is a
necessary part of any future salinity control program, it is
suggested that alternate types of linings for water convey-
ance channels be given consideration to determine if local
benefits can be increased. Specifically, the high costs of
concrete and gunnite may not be as desirable in terms of
total costs and benefits as a lining of lower initial cost,
but with somewhat higher maintenance costs.
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SECTION III
INTRODUCTION
Statement of the Problem
Salinity is the most pressing problem facing the future
development of water resources in the Colorado River Basin
(Fig. 1). Because of the progressive deterioration in min-
eral quality towards the lower reaches, the detrimental
effects of using an increasingly degraded water are first
seen in the lower basin. As a result of the continual
development in the upper basin, most of which will be div-
ersions out of the basin to meet large municipal and ind-
ustrial needs, water ordinarily available to dilute the salt
flows will be depleted from the system, causing significant
increases in salinity concentrations throughout the basin.
The economic penalty resulting from a use of lower quality
water will be incurred by those users in the lower system.
The U.S. Environmental Protection Agency (37) has estimated
that the present economic losses from salinity are $16 mil-
lion annually. If water resources development proceeds as
proposed without implementing a salinity control program,
the average annual economic detriments (1970 dollars) would
increase to $28 million in 1980 and $51 million in 2010 (37).
These damages do not reflect costs to Mexico.
A more detailed examination of the basin-wide problems is
summarized in Fig. 2 which clearly demonstrates the neces-
sity of attacking salinity basin wide. As indicated, the
bulk of the salt loads passing into the lower reaches is
attributable to the upper basin. Salinity management in the
upper basin must therefore concern itself with the aspect of
salt loading in the river system from municipal, industrial,
agricultural and natural sources. The other aspect, which
is the salt concentrating effects, is related to consumptive
use, evaporation, and transbasin diversions. Although sev-
eral methods of controlling salinity, such as phreatophyte
eradication (although controversial from a wildlife stand-
point) and evaporation suppression on reservoirs, are des-
irable, the most feasible solutions are in reducing_inflows
from mineralized springs and more efficient irrigation
practices. In any case, the salinity management objectives
in the upper basin must necessarily be concerned with a
reduction in the total salt load being carried to the lower
basin in order that the detrimental salinity effects anti-
cipated from further development can be limited. Salinity
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Fig. 1. The Colorado River Basin
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UPPER COLORADO RIVER
BASIN
AVERAGE SALT LOAD TONS/DAY
June 1965 - May 1966
NATURAL POINT SOURCES
AND WELLS
IRRIGATED AGRICULTURE
37%
(9645 T/d )
RUNOFF
52 %
(13728 T/d)
MUNICIPAL
357 T/d) AND
INDUSTRIAL
LOWER COLORADO RIVER
BASIN
AVERAGE SALT LOAD TONS/DAY
November 1963 - October 1964
UPPER COLORADO
v RIVER BASIN
^NATURAL \ INFLOW
POINT SOURCES \ _, 0.
(f. fo
(9833 T/d)
NET RUNOFF
MUNICIPAL
AND
INDUSTRIAL
(64 T/d)
IRRIGATED AGRICULTURE
Fig. 2. Relative magnitude of salt sources in the Colorado
River Basin (36).
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control must be practiced at all locations in the basin if
the economic losses to downstream users are to be minimized.
Since the Colorado River Basin is not a rapidly growing
municipal and industrail area, the pollution problems are
primarily associated with agriculture, as illustrated in
Fig. 2. Thus, a major aspect of reducing the salt inputs
in the upper basin must be the effective utilization of
the water presently diverted for irrigation by comprehen-
sive programs of conveyance channel lining, increasing irri-
gation efficiency on the farm, improved irrigation company
management practices, and more effective coordination of
local objectives between the various institutions in the
problem areas. Salinity is no longer a local problem and
should be considered regionally. In irrigated areas, it
is necessary to maintain an acceptable salt balance in the
crop root zone which requires some water for leaching.
However, when irrigation efficiency is low and conveyance
seepage losses are high, the additional deep percolation
losses are subject to the highly saline aquifers and soils
common in the basin and result in large quantities of salt
being picked up and carried back to the river system.
Therefore, a need exists to delineate the high input areas
and examine the management alternatives available to estab-
lish the most effective salinity control program. Probably
the most significant salt source in the upper basin is the
Grand Valley area (Fig. 3) in west central Colorado, which
was selected for this study in order to evaluate conveyance
lining as a possible salinity control practice.
The Study Area
The Colorado River enters the Grand Valley from the East,
is joined by the Gunnison River at Grand Junction, Colorado,
and then exits to the West. The contribution to the total
salt flows in the basin from this area, illustrated in
Fig. 4, is highly significant. The primary source of
salinity is from the extremely saline aquifers overlying
the marine deposited Mancos shale formation. The shale is
characterized by lenses of salt in the formation which are
dissolved by water from excessive irrigation and conveyance
seepage losses when it comes in contact with the Mancos
shale formation. The introduction of water through these
surface sources percolates into the shallow ground water
reservoir where the hydraulic gradients it produced displace
some water into the river. This displaced water has usually
had sufficient time to reach chemical equilibrium with the
salt concentrations of the soils and shale. These factors
also make the Grand Valley an important study area, since
-------
.-
• i.
Q
h
(U
B.
ffi
(,
o
!
0
M
PJ
:
Grand Valley Salinity
Control Demonstration
Project
v---/>% Gunn /son
River
-------
UPPER MAIN STEM
SUBBASIN
GRAND VALLEY AREA
r::r:;; 8 % mlllim
DUCHESNE RIVER
BASIN
//;;;;; GUNNISON RIVERA
BASIN
PRICE RIVER
LYMAN
AREA
OTHER AREAS
GREEN RIVER
SUBBASIN
LOWER MAIN STEM
SUBBASIN
SAN JUAN RIVER
SUBBASIN
Fig. 4. Relative magnitude of agricultural salt sources in
the Colorado River Basin (36).
10
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the conditions encountered in the valley are common to many
locations in the basin.
Purpose and Scope of the Study
Aside from the numerous studies in the Grand Valley to eval-
uate local conditions, this effort, the Grand Valley Salinity
Control Demonstration Project, is the first study conducted
in the area to determine the effect of a salinity management
practice on conditions in the basin. The project was funded
on a matching fund basis by the Environmental Protection
Agency in conjunction with the Grand Valley Water Users
Association, Palisade Irrigation District, Mesa County Irri-
gation Company, Grand Valley Irrigation Company, Redlands
Water and Power company, and the Grand Junction Drainage
District to further the development of pollution control
technology in the basin. Each of these entities had repres-
entatives on the Board of the Grand Valley Water Purifica-
tion Project, Inc., which was formed to contract with the
Federal government to conduct this demonstration project.
The objectives of the project include:
(1) Demonstration of the feasibility of reducing salt
loading in the Colorado River system by lining conveyance
channels to reduce unnecessary ground water additions.
(2) Extension of the results of this study to evaluate the
method for applicability to the problem in the Grand Valley
and upper basin.
The project is comprised of three study areas selected for
their different characteristics commonly found in the valley.
Area I, shown in Fig. 5, was chosen as an intensive study
area in which the bulk of the investigation was to be con-
ducted and also includes most of the construction effort.
This area was designated for detailed investigations regard-
ing effects of conveyance linings on the water and salt flow
systems in an irrigated area. The intensive study area was
selected for its accessibility in isolating most of the
important hydrologic parameters, but had the important advan-
tage that it allowed five irrigation companies to participate
in one unit. Area II was selected because it represented a
different land form several miles west of Area I along a
short section of the Grand Valley Canal where high seepage
losses had resulted in a severe drainage problem. Area III
is located along a section of the Redlands First Lift Canal,
which is supplied from the Gunnison River and was selected
to evaluate the effect of different drainage and soil types.
Both Areas II and III were to be studied with sufficient
11
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I
20
Scale
Mile
Canals
Drains
Boundary
Section Number
Government
Highline
Canal
Price Ditch
Grand Valley Canal
Mesa County
Ditch
Fig. 5. Intensive study area, Area I, of the Grand Valley Project,
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data to confirm the results in Area I and involved a mini-
mum number of observations.
Method of Approach
The procedure outlined for execution of the project consis-
ted of a two-phase study. Phase 1 was planned to evaluate
the conditions in the study areas prior to the construction
of the lining. These results have been reported (29).
Phase 2 consisted of re-evaluating the conditions after the
lining had been completed. In both cases, the study was
conducted to collect and analyze sufficient data to define
in detail both water and salt flow systems.
Although the pre-construction analysis has been reported,
all relevant information is presented herein in order to
provide a complete description of the results and conclusions
of this study.
Earlier investigations concerned with irrigation and drainage
in Grand Valley are summarized herein, as well as a history
of irrigation development in the valley.
The pre-construction and post-construction evaluation is
based upon a hydro-salinity model having two basic sub-systems
- surface water and ground water. The field data collection
is designed to define the components of the water and salt
budgets.
13
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SECTION IV
THE GRAND VALLEY AREA
Most salinity measures which could be considered may be
found to be very poorly conceived without a thorough under-
standing of the physical and social conditions in an area.
The attitudes of local people are important management con-
siderations and for the most part these attitudes are easily
traced to events surrounding the development of the area.
In addition, it is necessary to be aware of the natural
characteristics of an area so that restrictions are not
imposed which would destroy an area as a functional commun-
ity. And finally, the institutional structure of an area
should be known before control measures are undertaken so
that regional alternatives for meeting standards remain
flexible. In consideration of these aspects, this section
will briefly describe the development of Grand Valley and
present physical conditions.
Exploration and Settlement
Although numerous hieroglyphics and abandoned ruins testify
to occupation of the Colorado River Basin long before
settlement began, the first people encountered in the Grand
Valley were the Ute Indians. The first contact these
peoples had with white men was recorded in 1776 when an
expedition led by Fathers Dominiquez and Escalante passed
north of what was later to be Grand Junction and across the
Grand Mesa (12) . The region was subsequently visited by
fur trappers, traders and explorers. In 1839 one such
trader named Joseph Roubdeau built a trading post just
upstream from the present site of Grand Junction.
In 1853, Captain John W. Gunnison led an exploration party
into the Grand Valley from up the Gunnison River Valley in
search of a feasible transcontinental railroad route (2).
As Captain Gunnison and his party traversed the confluence
of the Colorado and Gunnison Rivers, an error was made by
the expedition recorder as to the proper naming of the
rivers. Beckwith referred to the Gunnison River as the
Grand River and the Colorado River as the Blue River, or
"nah-un-Kah-rea," as it was known to the Indians. The
mistake was later corrected, however, since the Colorado
River was known as the Grand River as early as 1842 (10) .
Field surveys conducted by Hayden (13) in 1875 and 1876
found only the Ute Indians in the valley, and skirmishes
15
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with some of the hostile Utes cut short the 1875 expedition.
As a result of the Meeker Massacre of 1879, the Utes were
forced to accept a treaty moving them out of Colorado and
onto reservations in eastern Utah. After the completion
of the Utes1 exit in September 1881, the valley was immed-
iately opened up for settlement with the first ranch
staked out on September 7, 1881 near Roubdeau's trading
post. Later that year on September 26, George A. Crawford
founded Grand Junction as a townsite and formed the Grand
Junction Town Company, October 10, 1881. On November 21,
1882 the Denver and Rio Grande Railroad narrow-gage line was
completed to Grand Junction via the Gunnison River Valley
and thus assured the success of the settlement.
Water Resource Development
Early exploration concluded that the Grand Valley had
limited potential for agriculture since the terrain appeared
very desolate. A great deal of appreciation for this judg-
ment can be acquired just passing through the area and not-
ing the landscape outside the irrigated agricultural bound-
aries. In 1853, Beckwith described the valley as, "The
Valley, twenty miles in diameter, enclosed by these moun-
tains, is quite level and very barren except scattered
fields of greasewood and sage varieties of artemisia - the
margins of the Grand (Gunnison) and Blue (Colorado) Rivers
affording but a meager supply of grass, cottonwood, and
willow." Soon after the settlement began, it was realized
that the climate could not support a non-irrigated agricul-
ture. As a result, irrigation companies were organized to
divert water from the river for irrigation. An attempt has
been made in the following paragraphs to describe this dev-
elopment in the Grand Valley.
Grand Valley Irrigation Company
The Grand Valley Irrigation Company owns and operates the
Grand Valley Canal, which at the present time serves 46,678
acres of land which can be broken down by type of land use
as listed in Table 1 (39).
The present Grand Valley Canal system comprising approxi-
mately 110 miles of canals and subcanals is the result of a
consolidation of the Grand River Ditch Company, Grand Valley
Canal Company, Mesa County Ditch Company, Pioneer Extension
Ditch Company, and the Independent Ranchmen's Ditch Associa-
tion. The construction of what is now the main line Grand
Valley Canal probably began in 1882, since the original
16
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Table 1. Land use under the Grand Valley Canal system
(including Mesa County Ditch).
Use
Corn
Sugar Beets
Potatoes
Tomatoes
Truck Crop
Barley
Oats
Wheat
Alfalfa
Native Grass Hay
Cultivated Grass and Hay
Pasture
Wetland Pasture
Native Grass Pasture
Orchard
Idle
Other Cropland
Subtotal
Farmsteads
Residential Yards
Urban
Stock Yards
Subtotal
Refineries
Other Industrial
Subtotal
Open Water Surfaces
Subtotal
Cottonwoods
Salt Cedar
Willows
Rushes or Cattails
Greasewood
Sagebrush or Rabbitbrush
Grasses and Sedges
Subtotal
Precipitation Only
Subtotal
Total
Acreage
6828
1726
96
133
147
2373
1530
63
5454
84
1621
3962
587
555
4557
11
Total
Percent
798
343
1402
138
433
4023
3591
29,727
63.7
5,540
682
798
11.9
1.5
1.6
6,340 13.6
3,591 7.7
46,678 100.0
17
-------
priority is dated August 22, 1882, although A. J. McCune who
was the engineer for the Grand River Ditch Company filed a
statement with the clerk and recorder of Mesa County, Colo-
rado on April 5, 1883 that construction commenced January 10,
1883 (27). At this time, the ditch was owned by Matt Arch,
E. S. Oldham, William Oldham, John Biggies, and William
Cline who planned for a capacity of about 786 cfs. However,
the early development times were uncertain and the company,
like many others, was facing financial trouble so was sold
to the Traveler's Insurance Company which also acquired title
to the other four companies now making up the system. On
January 29, 1894 the Grand Valley Irrigation Company was
incorporated when the Certificate of Incorporation was filed
with the Secretary of State's office and the title was
acquired from the insurance company.
The water rights of an agricultural area in the western
United States often are complex due to the nature of system
evolution necessary to develop an area. In general, such is
the case in the Grand Valley area. Upon the organization
of the company, an application was made for an adjudication
of its water rights from the Colorado River. The application
for the Grand Valley Canal was awarded a decree of 520.81 cfs
July 27, 1912, with the priority date of August 22, 1882,
which was priority No. 1 on the Colorado River. The hearings
which led to the adjudication established an irrigated acre-
age of 30-35 thousand acres with a probable 20% system loss
rate. On July 25, 1914, the First Enlargement of the Grand
Valley Canal was awarded Priority No. 358 and dated July 23,
1914 for 195.33 cfs, of which 75.86 cfs is conditional upon
the addition of 4,661.25 acres to the system.
Although the original decree was based on an estimated acre-
age of 30-35,000 acres, later investigation revealed the
acreage was slightly less than 40,000 acres, plus the addi-
tional 4,661.25 acres not yet developed, for a total of
about 44,000 acres. If the usual 200-day irrigation season
is experienced, this water right amounts to approximately
5.76 acre-feet per acre, from which an estimated 20% loss
rate of 1.05 acre-feet per acre leaves about 4.71 acre-feet
per acre for irrigation.
The company is organized in the corporation format. The
division of water among irrigators is on the basis of shares
of the capital stock of the company comprising a total of
48,000 shares. Thus, an individual holding one share of
stock would be entitled to 4.23 acre-feet of water at his
turnout. It should be noted that this figure does not
include the loss rates of the company. In addition, these
figures do not include the 75.86 cfs of conditional water.
In 1971, the water assessment was $15.00 for the first share
18
-------
and $2.40 for each additional share. Occasionally, some
assessments cannot be paid, in which case a period is given
for the irrigator to reclaim the water share, after which
grace period the share is sold at auction.
Grand Valley Project
The Grand Valley Project which now serves water to four
irrigation companies, the Grand Valley Water Users Associa-
tion, the Orchard Mesa Irrigation District, Palisade Irriga-
tion District (Price Ditch), and the Mesa County Irrigation
District (Stub Ditch), is the result of considerable effort
and a long series of disapointments. Before describing the
details of the companies themselves, it is interesting to
explore the history of development leading to the present
day conditions (1).
When the Ute Indians moved out of the valley and the first
benefits of irrigation were being realized, the opportunity
for further development of irrigation above and beyond the
Grand Valley Canal could be seen. The fruit industry pros-
pered almost from the time early settlers experimented with
deciduous fruit culture that eventually gave the valley a
reputation as a high quality orchard locality. However,
neither the capital nor the authorization to develop addi-
tional lands was available until 1902 when the Federal
Reclamation Act was passed. Although the act was passed,
no provision for operation was made. The Bureau of Public
Surveys was charged with the responsibility to investigate
locations which could be developed. Early in September 1902,
J. H. Mathis arrived in Grand Junction with a small party
of engineers to survey the Grand Valley for its feasibility
as an experimental reclamation project.
When the investigation was almost completed, an event
occurred which is probably the worst disaster to occur in
the valley. T. C. Henry, unscrupulous promoter from Denver,
arrived on the scene and convinced local people he could
finance, build and operate a system far better than could
the government. By a majority of two votes, the local
citizens accepted the proposal, causing the government to
withdraw, even though the engineers had found Grand Valley
to be a feasible location for a reclamation project.
In 1904, T. C. Henry was forced to admit that he had neither
a plan nor a prospect for action in the Grand Valley. For-
tunately, the efforts of the people were sufficient to revive
government interest in the potential project. In June 1907,
James R. Garfield, Secretary of the Interior, officially
approved the project and allocated $150,880 to begin the
19
-------
permanent survey of the project. The project at this point
entailed what is now known as the Government Highline Canal
and its construction was increasingly important to the local
people because of the continued success agriculture had been
enjoying. In fact, the future of the fruit industry looked
so promising that one six-acre peach orchard sold for $24,000,
or $4,000 per acre.
The Grand Valley was not yet through with T. C. Henry. In
1907, he contacted the Magenheimer Brothers of Chicago who
had been successful in dredging operations along Lake Michi-
gan. Since the exploitation of irrigation projects was both
a popular and a successful business, they took up the line.
Together with four local promoters, they organized a district
(later to become the Orchard Mesa Irrigation District) cover-
ing about 10,000 acres on the south side of the river. In
addition, plans were being made by the Magenheimers to take
over the remainder of the land of the government project
(Water Users Association).
The increasing demand for the project prompted the local
people in the Association to submit a proposal to provide
$125,000, if the government would match this amount, for
starting construction. In October 1908, Secretary Garfield
accepted the challenge and approved the proposal. Local
pledges in the form of work allocations were soon called upon
and construction began; but at four o'clock on May 4, 1909,
the same day work started, the new Secretary of the Interior,
R. A. Ballenger, suspended construction with no reason sta-
ted. Ballenger had been asked by Senator Henry M. Teller
from Denver to abandon the project because private capital
was available for the work and in such cases the government
should not interfere. This information had been given the
Senator by a prominent law firm of Denver which was repres-
enting the Magenheimer-Henry combination. The local people
sent representatives to Washington to investigate the work
stoppage and just happened to visit Senator Teller, who
then told them what had happened. Unfortunately, a great
deal of effort by numerous individuals failed to sway
Ballenger, who still would not give reason for his attitude.
In 1911, Ballenger resigned and was succeeded by Walter L.
Fisher who finally gave his approval; and on October 23, 1912
work was again initiated. Thus, the Association escaped
falling into the hands of the Magenheimers.
The construction of the Orchard Mesa system was begun by
placing a $163 per acre cost on the 10,000 acres of land,
with six percent interest bearing bonds and warrants. The
system was so poorly constructed that portions failed before
the system was completed. This was all made possible because
the Magenheimers had gained control of the Board of Directors,
20
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and although the idea was met with bitter opposition by loc-
al people the election carried. From that time on, T. C.
Henry and the Magenheimers embezzled the farmers and the
district to the point of final collapse. Phony construction
companies, phony construction and phony personnel finally
brought the district near financial collapse.
Finally, an earnest plea was made to the government that
rehabilitation of the Orchard Mesa system be included among
the construction efforts with the Association. The plea
was heeded and the system saved, a cost which is still being
repaid.
The efforts of T. C. Henry and the Magenheimer Brothers
are not unlike many that have occurred throughout the West.
Many people were ruined by their actions and the memory is
still very real. It is very fortunate that the irrigation
companies in the Grand Valley and many other areas are still
operating.
With this abbreviated history surrounding the Grand Valley
Project, the operation and water rights of the 4-canal system
will be discussed separately.
Grand Valley Water Users Association. The Grand Valley Water
Users Association was incorporated February 7, 1905 and later
renewed the incorporation September 11, 1945. It operates
the Government Highline Canal which serves about 44,416 acres
of irrigable land. In addition, the Association diverts 800
cfs during the non-irrigation season for power development
through a siphon across the Colorado River shortly below the
main diversion. During the irrigation season, 400 cfs is
used for power development, with the remaining 400 cfs
passing through the irrigation pumps. The power generated
with this water is sold to the Public Service Company of
Colorado to help pay the debt on the original project.
A summary of the water rights is listed in Table 2 and will
be referred to later in the descriptions of the other canals .
The land use survey conducted in 1969 under the Government
Highline Canal, which is listed in Table 3 (39), varies
somewhat from that originally listed by the early land sur-
veyors. However, the classification systems are also diff-
erent.
The operation of the Grand Valley Water Users Association is
on a corporation basis, and although stock is registered in
the County Recorder's Office, none has ever been issued.
The Bureau of Reclamation classified the land into one of
five categories: Class 1 - good orchard; Class 1A - young
21
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Table 2. Water right decrees for the Grand Valley Project.
Name
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
of Ditch
Orchard Mesa Power
Canal
Palisade Irr. Dist.
it ii n
Orchard Mesa Power
Canal
E. Palisade Irr.
Dist.
Mesa County Irr.
Dist.
n ti »
Mann Pumping System
Orchard Mesa Irr.
Dist.
n ii n
n M n
Grand Valley Project
n n n
Rose Point Power
Canal
Orchard Mesa Irr.
Dist.
Palisade Irr. Dist.
Original
Appropriation
Date
3- 6-89
10- 1-89
ii n
8- 2-98
10- 1-00
7- 6-03
ii ii
9-10-03
10-25-07
n M
it n
2-27-08
ii n
7- 2-10
4-26-14
6- 1-18
Decree
Allowed
(cfs)
110.70
573.00
80.00
139.30
10.20
627.00
40.00
1.00
195.00
75.00
180.00
730.00
400/800
113.25
100.00
23.50
Use
of
Right
Irrigation
Pumping
Irrigation
Irrigation
Irrigation
Pumping
Irrigation
Irrigation
Irr , Pump
Irrigation
Conditional
Irrigation
Power
Irrigation
Conditional
Irrigation
22
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Table 2. (Continued)
Comments
(1) Abandon, land now in Orchard Mesa Irr. Dist., 10 cfs irr.,
rest pumping, rights not transferred to District.
(2) Power plant abandon, decree usable only with approval of
Bureau of Reclamation.
(3) Decree delivered by Gov't Highline Canal, point of diversion
changed by decree of 7-25-41.
(4) Same as (1) .
(5) former steam pumping plant, now gravity from Orchard Mesa Power
Canal, Orchard Mesa Irr. Dist. owns decree.
(6) Same as (2) .
(7) Decree now delivered by Gov't Highline Canal by gravity and
pumping, point of diversion not formally changed.
(8) Former steam pump from river, now pumped from Orchard Mesa
Power Canal, electric motor.
(9) Now diverted through Gov't Highline Canal, but through same
pumping plant, point of diversion changed.
(10) Same as (9) .
(11) Same as (9), made absolute in decree of 7-25-41, 130.0 cfs
power, 50 cfs irrig.
(12) Quantity fixed in decree of 7-25-41 as above, same applies
for power and domestic.
(13) Quantity fixed in decree 7-25-41 with priority date as above,
400 cfs irrigation season, 800 cfs non-irrigating season.
(14) Abandon, decree property of Orchard Mesa Irr. Dist., no change
in point of diversion.
(15) Conditional water claimed for irrigation, none claimed for
pumping water.
(16) Date of this decree is date of change of point of diversion
to Gov't Highline Canal (3). This decree provides for
laterals fed directly from project canal to Palisade lands.
23
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Table 3. Land use under the Government Highline Canal in 1969
Use
Corn
Sugar Beets
Potatoes
Tomatoes
Truck Crop
Barley
Oats
Wheat
Alfalfa
Native Grass Hay
Cultivated Grass and Hay
Pasture
Wetland Pasture
Native Grass Pasture
Orchard
Idle
Other Cropland
Subtotal
Farmsteads
Residential Yards
Urban
Stock Yards
Subtotal
Refineries
Other Industrial
Subtotal
Open Water Surfaces
Subtotal
Cottonwoods
Salt Cedar
Willows
Rushes or Cattails
Greasewood
Sagebrush or Rabbitbrush
Grasses and Sedges
Subtotal
Precipitation Only
Subtotal
Total
Acreage
Total
Percent
0
0
635
10,429
25,169 56.7
1,629
3.7
0 0
635 1.4
6,554
10,429
44,416
14.8
23.4
100.0
24
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orchard; Class 2 - good agricultural lands; Class 3 - fair
agricultural; and Class 4 - poor agricultural lands. On the
basis of this classification, a farmer can sign up for his
irrigable acreage which allows him at the present time four
acre-feet per acre, above which (if the supply is available)
he is charged for the excess. There are restrictions on the
time rate of delivery, however, which are imposed when the
supply is limited. This restriction is usually a limit of
1 cfs per 40 acres, and sometimes as low as 0.75 cfs per
40 irrigable acres; this practice has, in the past, been
necessary only during the peak use months of the summer.
During the fall and spring, water is usually delivered on a
demand basis. It should be further noted that although a
farmer signs up for a fixed area of irrigable acreage, he
may apply the water as he wishes on his property. In addi-
tion, when the property is sold, he is allowed only to sell
water for the irrigable acreage being sold, so in effect the
water is tied to the land and non-shareholders or outside
acreage cannot obtain Association water.
The price of water in the Association is based on an assess-
ment of the irrigable acreage on the following basis: In
1971, for example
$1.40/acre repayment of government land
$4.00/acre for operation and maintenance
$1.20/acre-ft of excess used over 4 acre ft/
acre allocated.
The minimum assessment is $20 per farm. In 1971, there were
approximately 24,000 acres assessed as compared with the
25,000 irrigable acres (39).
Orchard Mesa Irrigation District. The Orchard Mesa Division
of the Grand Valley Project was formed by request of the
people of the Orchard Mesa Irrigation District when the prior
operation was facing bankruptcy. The District was organized
under the 1905 Colorado Statute covering irrigation districts,
which was later revised to the 1921 Colorado Law.
The operation of the district in many ways is similar to the
Association in that the water duty and land classification
are the same. The Orchard Mesa Irrigation District is now
provided water through a siphon diversion from the Government
Highline Canal into the Orchard Mesa Power Canal. During the
irrigation season, 1/2 of the 800 cfs in the canal is diver-
ted through the Orchard Mesa Irrigation District pumps which
lift 80 cfs 40 feet into the Orchard Mesa #2 Canal and 60 cfs
130 feet into the Orchard Mesa #1 Canal.
The price of using water in the District is based again on the
land classification. However, the procedure is similar to the
25
-------
assessment technique used by county government. The Board
of Directors for the District prepares a budget consisting
of repayment for irrigation system rehabilitation by the
government, operation and maintenance, etc. Then, the
budget is approved by the Tax Commission of Colorado and
the State Auditor. The valuation of land is then checked
with the County Assessor, from which a mill levy is set to
obtain the money. In 1971, the assessed acreage was 9,199
acres, which was assessed on the following basis:
Class 1 $11.05/acre
Class 1A 8.71/acre
Class 2 8.71/acre
Class 3 7.15/acre
Class 4 5.85/acre
Of the total revenue collected, at a rate of 130 mills, 43
goes to repay the government and 87 for operation and main-
tenance. The 1969 land use breakdown in the District is
summarized in Table 4 (39).
Palisade Irrigation District. The Palisade Irrigation Dist-
rict, with essentially the same organizational format as
the Orchard Mesa Irrigation District, operates the Price
Ditch. This ditch is supplied 66-68 cfs through a turbine
pump just off the Government Highline Canal as it exits
through Tunnel No. 3. An additional 24-22 cfs is delivered
through turnouts in the Highline Canal, as can be noted in
Table 2. The agricultural area served by the Price Ditch is
listed in Table 5 (39) .
Both the Palisade Irrigation District and the Mesa County
Irrigation District were organized independently of the
government projects. Their history is somewhat unknown to
the writers, but they consolidated their systems with the
Highline Canal when it was built, presumably to streamline
their operation.
Mesa County Irrigation District. The Mesa County Irriga-
tion District, which operates the Stub Ditch, has an irriga-
tion water right of 40 cfs as listed in Table 2. The
operation and organization of this district are similar to
the previous five districts mentioned. At the turbine pump
serving the Price Ditch, 15 cfs is pumped into the Stub
Ditch, with the remaining 25 cfs being diverted directly
from the Highline Canal to agricultural lands within the
boundaries of the Mesa County Irrigation District. The
irrigated land under the Stub Ditch is included in Table 6
(39).
26
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Table 4. Land use in the Orchard Mesa Irrigation District
during 1969 (39).
Use Acreage Total Percent
Corn 767
Sugar Beets 51
Potatoes 78
Tomatoes 66
Truck Crop 53
Barley 247
Oats 82
Wheat 26
Alfalfa 948
Native Grass Hay 20
Cultivated Grass and Hay 213
Pasture 597
Wetland Pasture 144
Orchard 3493
Idle 909
Other Cropland 0
Subtotal 7,694 69.9
Farmsteads 234
Residential Yards 244
Urban 703
Stock Yards 182
Subtotal 1,363 12.4
Refineries 0
Other Industrial 0
Subtotal 0 0
Open Water Surfaces 135
Subtotal 135 1.2
Cottonwoods
Salt Cedar
Willows
Rushes or Cattails
Greasewood
Sagebrush or Rabbitbrush
Grasses and Sedges
Subtotal 850 7.7
Precipitation Only 964
Subtotal 964 8.8
Total 11,006 100.0
27
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Table 5. Land use under the Price Ditch during 1969 (39).
Use Acreage Total Percent
Corn 535
Sugar Beets
Potatoes
Tomatoes 2
Truck Crop
Barley 263
Oats 70
Wheat 22
Alfalfa 551
Native Grass Hay 35
Cultivated Grass and Hay 109
Pasture 369
Wetland Pasture
Native Grass Pasture 198
Orchard 1575
Idle 571
Other Cropland 6
Subtotal 4,306 79.7
Farmsteads 108
Residential Yards 163
Urban 264
Stock Yards 12
Subtotal 547 10.1
Refineries 0
Other Industrial 0_
Subtotal 0 0
Open Water Surfaces 37
Subtotal 37 0.7
Cottonwoods
Salt Cedar
Willows
Rushes or Cattails
Greasewood
Sagebrush or Rabbitbrush
Grasses and Sedges
Subtotal 177 3.3
Precipitation Only
Subtotal 337 6.2
Total 5,404 100.0
28
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Table 6. Land use under the Stub Ditch during 1969 (39).
Use Acreage Total Percent
Corn 71
Sugar Beets
Potatoes
Tomatoes
Truck Crop 33
Barley
Oats
Wheat
Alfalfa 97
Native Grass Hay
Cultivated Grass and Hay 6
Pasture 43
Wetland Pasture
Native Grass Pasture
Orchard
Idle
Other Cropland
Subtotal 608 78.7
Farmsteads
Residential Yards
Urban
Stock Yards
Subtotal 32 4.1
Refineries 0
Other Industrial 0.
Subtotal 0 0
Open Water Surfaces 31
Subtotal 31 4.0
Cottonwoods 4
Salt Cedar 2
Willows 7
Rushes or Cattails
Greasewood 38
Sagebrush or Rabbitbrush
Grasses and Sedges
Subtotal 51 6.6
Precipitation Only 51
Subtotal 51 6.6
Total 773 100.0
29
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Redlands Water & Power Company
The Redlands Water & Power Company, a mutual ditch company,
irrigates about 3,000 acres southwest of Grand Junction and
south of the Colorado River. The water supply is diverted
from the Gunnison River in a canal carrying 670 cfs. Six
cfs is used for irrigation of lands below the power canal,
610 cfs for power generation, and 54 cfs is pumped to an
initial height of 127 feet for irrigation. Small areas in
the project are served by higher lifts, the highest being
at about 300 feet. Electricity in excess of pumping needs
is sold to project settlers and to the Public Service Com-
pany. Land use classification resulting from the 1969 survey
is listed in Table 7 (39).
Geology
The plateaus and mountains in the Colorado River Basin are
the product of a series of uplifted land masses deeply
eroded by wind and water. However, long before the earth
movements which created the uplifted land masses, the region
was the scene of alternate encroachment and retreat of great
inland seas. The sedimentary rock formations underlying
large portions of the basin are the result of material accu-
mulated at the bottom of these seas. In areas similar to
the Grand Valley, the upper portions contain a large number
of intertonguing and overlapping formations of continental
sandstone and marine shales, as shown in Fig. 6 (31) . The
lower parts are mostly marine Mancos shale and the Mesa Verde
group of related formations. This particular geology is
exhibited in about 23 percent of the basin in such common
locations as the Book Cliffs, Wasatch, Aquarius, and Kaipar-
owits Plateaus, the cliffs around Black Mesa, and large areas
in the San Juan and Rocky Mountains.
The geology of an area has a profound influence on the
occurrence, behavior, and chemical quality of the water res-
ources. In the mountainous origins of most water supplies,
a continuous interaction of surface water and ground water
occurs when precipitation in the form of rain and melting
snow enters ground water reservoirs. Eventually, these
quantities of ground water return to the surface flows
through springs, seeps, and adjacent soil in regions down-
stream. A further consequence of such a flow system is the
addition of water from streams to the ground water storage
during periods of high flows and subsequent return flows
during low flow periods. The resulting continuous interac-
tion of surface water and ground water allows contact with
rocks and soils of the region which affect the chemical char-
acteristics imparted to the water.
30
-------
Table 7. Land use under the Redlands Water & Power
Company system during 1969 (39) .
Use Acreage Total Percent
Corn 124
Sugar Beets 32
Potatoes 3
Tomatoes 17
Truck Crop
Barley 18
Oats 55
Wheat
Alfalfa 531
Native Grass Hay
Cultivated Grass and Hay 31
Pasture 1139
Wetland Pasture
Native Grass Pasture 115
Orchard 371
Idle 610
Other Cropland 0_
Subtotal 3,046 47.5
Farmsteads 94
Residential Yards 38
Urban 713
Stock Yards 40
Subtotal 885 13.8
Refineries 0
Other Industrial 0_
Subtotal 0 0
Open Water Surfaces 63
Subtotal 63 1.0
Cottonwoods
Salt Cedar
Willows
Rushes or Cattails
Greasewood
Sagebrush or Rabbitbrush
Grasses and Sedges
Subtotal 1,202 18.7
Precipitation Only 1235
Subtotal 1,235 19.0
Total 6,431 100.0
31
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UNCOMPAHGRE UPLIFT
GRAND MESA
CENOZOIC
'j~ GRANITE ,' GN'E'ISS ' — \ '
-__ AMPHIBOLITE , ETC .. /
•
[ .
ARCHEZOIC
Fig. 6. General geologic cross-section of the Grand Valley (31).
-------
The interior valleys of the basin (the Grand Valley is a good
example) do not receive large enough amounts of precipitation
to significantly recharge the ground water storage. Usually,
the water bearing aquifers are buried deep below the valley
floor and are fed in and along the high precipitation areas
of the mountains. Shallow ground water supplies are predom-
inately the result of irrigation. Although the water in the
consolidated rock formations of the valley region does not
contribute significantly to the stream flows as is the case
in higher elevations, it does have a pronounced effect on
water quality due to the large volumes of natural salts con-
tained in these formations. High intensity thunderstorms
bring surface runoff in contact with the rocks and soils
which then distribute their chemical characteristics. Erosion
by rivers and streams has deposited alluvium high in natural
salts along certain valleys, with these natural salts being
returned to the surface waters when moisture, from either
precipitation or irrigation, percolates through the alluvial
soils.
Soils
The physical features describing the test area are similar to
the entire Grand Valley. The soils in the area were classi-
fied by the Soil Conservation Service in cooperation with
the Colorado Agricultural Experiment Station (31) in 1940.
Soil classifications in the project intensive study area are
shown in Fig. 7. The soil classification symbols, along with
a general description of each symbol, are tabulated in Table 8.
The desert climate of the area has restricted the growth of
natural vegetation, thereby causing the soils to be very low
in nitrogen content because of the absence of organic matter.
The natural inorganic content is high in lime carbonate,
gymsum, and sodium, potassium, magnesium, and calcium salts.
With the addition of irrigation, some locations have exper-
ienced high salt concentrations with a resulting decrease in
crop productivity. Although natural phosphate exists in the
soils, it becomes available too slowly for use by cultivated
crops and a fertilizer application greatly aids yields. Other
minor elements such as iron are available except in those
areas where drainage is inadequate. The soils in the test
area are of relatively recent origin as they contain no def-
inite concentration of lime or clay in the subsoil as could
be expected in weathered soils. Some areas in the valley
have limited farming use because of poor internal drainage,
which results in water logging and salt accumulations.
33
-------
ll..
Grand Valley Canal
Stub Ditch
Government
Highline Canal
Price Ditch
Fig. 7. Soil classification map of intensive study area, Area I (31).
-------
Table 8. Soil mapping classification index (31).
Map Symbol Soil
Be Billings silty clay loam, 0 to 2 percent slopes
Ba Billings silty clay, 0 to 2 percent slopes
Be Billings silty clay, moderately deep over Green
River soil material, 0 to 2 percent slopes
Gm Green River very fine sandy loam, deep over gravel,
0 to 2 percent slopes
Gk Green River fine sandy loam, deep over gravel,
0 to 2 percent slopes
Cc Chipeta-Persayo silty clay loams, 5 to 10 percent
slopes
Bd Billings silty clay loam, 2 to 5 percent slopes
Pb Persayo-Chipeta silty clay loams, 2 to 5 percent
slopes
Rf Ravola very fine sandy loam, 0 to 2 percent slopes
Re Ravola loam, 0 to 2 percent slopes
Ro Riverwash, 0 to 2 percent slopes
Rb Ravola clay loam, 0 to 2 percent slopes
Rs Rough gullied land
Ra Ravola fine sandy loam, 0 to 2 percent slopes
35
-------
Lying on top of the Mancos shale and below the alluvial soils
is a large cobble aquifer extending north from the river to
about midway up the test area, as illustrated by Fig. 8.
The importance of this aquifer with respect to the drainage
problems of the area has been demonstrated by a cooperative
study in 1951 between the Colorado Experiment Station in
conjunction with the Agricultural Research Service (ARS)
(30), which evaluated the feasibility of pump drainage from
the aquifer.
Land Use Survey
Evaporation and transpiration from crops, phreatophytes,
and other land uses results in a loss of salt-free water to
the atmosphere and a deposition of salt in the soil profile.
The magnitude of these losses depends on the acreage of each
water use. As a part of a valley wide evaluation, the var-
ious acreages of land uses in Area I were mapped according
to the index presented in Table 9. The acreages for each
land use are shown in Table 10 (39). One of the most quoted
statements in the literature concerning the Grand Valley is
that approximately 30% of the farmable area is unproductive
because of the ineffectiveness of the drainage in these
areas. Examination of the results presented in Table 10
indicates that 70% of the study area can be classified as
irrigable land, however only 52% can be considered produc-
tive. The use of the term productive relates to the areas
producing cash crops such as corn, beets, grains, orchards,
alfalfa, etc. The land use summary for the entire valley
will be presented in a later section.
Climate
The mountain ranges in the Upper Colorado River Basin have
much more influence on the climate than does the latitude.
The movement of air masses is disturbed by the mountain
ranges to the extent that the high elevations are wet and
cool, whereas the low plateaus and valleys are drier and
subject to wide temperature ranges. A common characteristic
of the climate in the lower altitudes is hot and dry summers
and cold winters. Moist Pacific air masses can move across
the basin, but dry polar air and moist tropical air rarely
continue all the way across the basin. Movement of both
types of air mass is obstructed and deflected by the moun-
tains so that their effects within the basin are weaker and
more erratic than in most areas of the country.
36
-------
Mancos Shale
Cobble Aquifer
Tight Clay
Fine Gravel
Normal Soils
Fig. 8. Cross-sections of soil Profiles in Area I.
31
-------
Table 9. Land use mapping index,
Irrigated Cropland
1. Corn
2. Sugar beets
3. Potatoes
4. Peas
5. Tomatoes
6. Truck crop
7. Barley
8. Oats
9. Wheat
10. Alfalfa
11. Native grass hay
12. Cultivated grass and hay
13. Pasture
14. Wetland Pasture
15. Native grass pasture
16. Orchard
17. Idle
18. Other
B. Dry Cropland
1. Alfalfa
2. Wheat
3. Barley
4. Beans
5. Cultivated grasses
6. Fallow
7. Other
D. Industrial
1. Power Plants
2. Refineries
3. Meat Packing
4. Other
E. Open Water Surfaces
1. Major storage
2. Holding storage
3. Sump ponds
4. Natural ponds
F. Phreatophytes
1. Cottonwood
2. Salt Cedar
3. Willows
4. Rushes or Cattails
5. Greasewood
6. Sagebrush and/or rabbit-
brush
7. Wildrose, Squawberry,
etc.
8. Grasses and/or Sedges
9. Atriflex
Precipitation only
Other Land Use
1. Farmsteads
2. Residential yards
3. Urban
4. Stock yards
38
-------
Table 10. Land use in Area I during 1969 (39)
Classification Acreage Percent
Al Corn 487
A2 Sugar beets 1
A3 Potatoes 8
A7 Barley 255
A8 Oats 14
A9 Wheat 9
A10 Alfalfa 545
A12 Cultivated grass and hay 141
A13 Pasture 476
A15 Native grass pasture 387
A16 Orchard 349
A17 Idle 559
A18 Other 6_
Subtotal 3237 69.9
Cl Farmsteads 258
C2 Residential yards 61
C3 Urban 85
C4 Stockyards 8_
Subtotal 412 8,9
E4 Open water surfaces 70
Subtotal 70 1.5
F1L Cottonwood (light) 3
F1H Cottonwood (heavy) 3
F2M Salt cedar (medium) 15
F2H Salt cedar (heavy) 253
F3L Willows (light) 7
F3H Willows (heavy) 63
F4L Rushes (light) 1
F4H Rushes (heavy) 9
F5L Greasewood (light) 67
F5M Greasewood (medium) 104
F5H Greasewood (heavy) 162
Subtotal 687 14.8
Precipitation only 225
Subtotal 225 4.9
100.0
39
-------
Most of the precipitation to the basin is provided from the
Pacific Ocean and the Gulf of Mexico whose shores are 600
and 1000 miles from the center of the basin, respectively.
The air masses are forced to high altitudes and lose much of
their precipitation before entering the basin. During the
period from October to April, Pacific moisture is predomin-
ant, but the late spring and summer months receive moisture
from the Gulf of Mexico.
The monthly distribution of precipitation and temperature
for Grand Junction is shown in Fig. 9 (33). The climate in
the area is marked by a wide seasonal range, but sudden or
severe weather changes are infrequent due mainly to the
high ring of mountains around the valley. This protective
topography results in a relatively low annual precipitation
of approximately eight inches. The usual occurrence of
precipitation during the growing season is in the form of
light showers from thunderstorms which develop over the
western mountains. The nature of the valley location with
typical valley breezes provides some spring and fall frost
protection resulting in an average growing season of 190
days from April to October. Although temperatures have
ranged to as high as 105°F, the usual summer temperatures
range in the middle and low 90's in the daytime to the low
60's at night. Relative humidity is usually low during the
growing season, which is common in all of the semi-arid
Colorado River Basin.
Irrigation
The system of irrigation most common to the area is surface
flooding either by borders or furrows. The study area it-
self is located in the narrow eastern part of the valley
which has a relief of about 50 feet per mile sloping south
towards the river. As a result, care is taken to prevent
erosion in most cases by irrigation with small streams.
Most farms in the area are small and have short run lengths.
However, the small irrigation stream allows adequate appli-
cation. The quantity of water delivered to the farmer is
plentiful so the usual practice is to allow self-regulated
diversions. Although the method of irrigation is quite
similar throughout Grand Valley, there is considerable con-
trast in land use. The lands at the upper end (eastern) of
the valley are largely orchards, which is also the case for
the Orchard Mesa lands, which are south of the Colorado
River. In contrast to the intensive study area, larger
tracts of farm land are located in the western portions of
the valley, with many of these lands having good soils which
contribute to the production of high yield crops.
40
-------
GRAND JUNCTION, COLO.
Alt. 4843 ft.
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:;:::::::::: :>:X'i:::: !$•::::$ :::•:::::•::
:::::::x-: -x-xX; xXvX X;Xv:;
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?:X:5: xiv'-X; x'Sx^ x'^:S
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Fig. 9. Normal precipitation and temperature at Grand
Junction, Colorado.
41
-------
SECTION V
SUMMARY OF PREVIOUS RESEARCH
Although the first engineering investigations in the region
were conducted to establish the feasibility of developing
additional irrigated land, almost every study since has
been in some way related to salinity. The early settlers
were able to dig shallow fresh water wells, but as irriga-
tion continued, the ground water became too saline for any
use. Not until low lying lands began to show signs of
high water tables, and older apple orchards began to fail,
was the necessity for salinity investigations realized.
With the saline soil conditions and natural composition of
the soil producing a very low internal drainage capacity,
the lapse between first irrigation and the following salin-
ity crisis was about twenty years. This seemingly protrac-
ted period would have been greatly reduced if the expansion
of the irrigated acreage to the higher regions had been
accomplished earlier since the deep percolation from the
higher elevations would have added to the drainage require-
ment in the low lands.
In addition to the drainage and salinity investigations,
numerous experiments have been performed to evaluate crop
production factors. Many experiments deal exclusively with
the agronomic variables. Studies related to the salinity
problem in the Grand Valley can be classified according to
objective:
(1) Local hydrologic and salinity studies. These studies
have been undertaken to define the important hydrologic
parameters in the valley so that problem areas can be delin-
eated and alternate solutions examined. Among the investi-
gations in this group are drainage, conveyance seepage, irri-
gation efficiency, and salinity studies.
(2) Regional hydrologic and salinity studies. When the
deleterious impact of an ever-increasing salinity concentra-
tion in the basin was realized, the necessity for basin wide
planning of salinity control measures was apparent. In
order to effectively outline alternatives, extensive reconn-
aissance level studies were needed to collect data, delineate
problem areas, and enumerate alternative actions.
(3) Local salinity control project investigations. After
having determined basin salt inputs, the next step in salin-
ity control is to investigate the feasibility of implementing
the different courses of action which could be followed to
alleviate the problem.
43
-------
The initiation of the study reported herein marked the beg-
inning of the third type of investigation described above.
This section of the report summarizes several of the more
significant results obtained from prior studies directed
toward the first two objectives listed above.
Local Hydrologic and Salinity Investigations
Drainage
Although many early settlers attested to the seriousness of
the drainage problems in the low lying lands of the valley,
the conditions were alarming by about 1914. In 1908, D. G.
Miller, Senior Drainage Engineer, Bureau of Public Roads and
Rural Engineering, initiated an eight-year investigation of
the problem covering the irrigated acreage which was served
by the Grand Valley Irrigation Company (21). The objective
of the study was to point out the contributary causes of the
high water table condition in the valley, and to emphasize
the necessity of drainage as a remedy. Observations were
made throughout the region to determine water quality of
soil extracts and ground water, water table elevations, and
the effects of high water table conditions.
The early manifestations of injury due to alkalinity in the
Grand Valley were first realized when regions in the more
mature apple orchards began to fail. Almost invariably,
when the older trees died, younger trees would still grow
owing to their shallower rooting system. Eventually, even
field crops failed, so that finally the land in many cases
became unproductive. Soon after the causes of crop failure
had been somewhat determined, several farms were selected
in the valley where the influence of the Mancos Shale could
be studied. At one point in the study, 392 soil samples
were taken on which a constituent breakdown was performed on
the soil extract. The following was the result of these
tests:
Calcium Sulfate 49.5%
Sodium Chloride 13.6%
Sodium Sulfate 10.4%
Magnedium Sulfate 9.7%
Bicarbonate 7.5%
Calcium Chloride 2.1%
Magnesium Chloride 1.6%
Nitrates 2.1%
In addition, water samples were taken from wells that had
been drilled to the shale. Also, samples were collected
from 1,000 feet of drainage tile connecting six wells
44
-------
drilled into a water bearing strata in the Mancos Shale.
Two samples collected May 8, 1914 and March 30, 1915 provid-
ed the following results:
May 8, 1914 March 30, 1915
Sulfuric Acid 13,320 mg/1 10,508 mg/1
Bicarbonic Acid (HCO3) 632 mg/1 513 mg/1
Nitric Acid 832 mg/1 286 mg/1
Chlorine 490 mg/1 262 mg/1
Calcium 425 mg/1 405 mg/1
Magnesium 873 mg/1 600 mg/1
Sodium 5,904 mg/1 3,901 mg/1
TOTAL 21,671 mg/1 16,475 mg/1
Although the results of these analyses are in a form no lon-
ger used, they do provide a useful indication of the mineral
quality characteristic of the samples. The realtively high
content of nitrates (around 1204 ppm) in some of the samples
taken in close proximity to the shale is expected of shale
formed from Cretaceous and Tertiary formations.
Examination of wells and piezometers located in the cobble
aquifer beneath the soil indicated an upward pressure grad-
ient which could be responsible for areas of high water
table. Although the shale beneath the cobble and the imper-
vious clay layer immediately above provide a confining effect,
these conditions are not wholly continuous, resulting in
areas within a uniform topographic region, which exhibit
varying water table heights. The tight nature of the soils
was also determined to be the cause of alkalinity problems in
areas where the water table was not exceedingly high. For
example, some areas showed an alkaline condition when the
water table was as much as eight feet below the surface.
This was thought to be the result of capillary action in the
soils.
The conclusions formulated from this report had much to do
with the organization of the Drainage District in 1924.
Some of the pertinent results of the 1908-15 study include:
(1) Drainage in the Grand Valley, because of the magnitude
of the problem, must be a regional undertaking in three
types of drainage. These are (a) relief of the pressure
condition existing in the cobble aquifer, (b) interception
of canal and lateral seepage and excessive irrigation from
irrigated land in the higher parts of the valley, and (c)
lateral drainage of the water logged soils in locations
where natural drainage is entirely deficient.
(2) The positive hydraulic gradients in the aquifer are
significant in numerous locales, but rarely sufficient to
bring the water within three to six feet of the surface.
45
-------
Consequently, high water tables were probably the result of
excessive irrigation and seepage.
(3) The analysis of soil samples and ground water samples
showed a definite and direct relation between the quantities
of nitrate in the samples and the total soluble salts. The
percentage of nitrate increases as samples are collected
closer to the shale. As a result, the solution of the alka-
line problem, irrespective of the source of the nitrates,
will eliminate the problem completely. Further, those salts
that do remain in the soils can be easily ammended by stand-
ard methods.
The results of the investigation showed that a thorough sys-
tem of drainage based upon a full knowledge and appreciation
of underlying conditions would improve the production on
about 30% of the irrigated acreage in the valley lying imm-
ediately adjacent to the Colorado River. In the early 1940's
it was clear that most of the open drains that had been exca-
vated to alleviate the drainage problems in critical areas
were ineffective. The effectiveness of drainage depends to
a large extent upon the permeability of the soil and the
nature of the substrata. In order for drains to reduce the
flow of ground water, one of the highly permeable strata must
be intercepted. Specifically, for those lands where drainage
is the most inadequate, the cobble aquifer should be tapped.
In early 1946, an investigation was launched by the Soil Con-
servation Service (SCS) on the "Willsea" farm west of Grand
Junction (8). Piezometer readings indicated the presence of
a vertical gradient of 0.48 ft/ft. As an open drain on the
north side of the farm had little effect on the problem, it
was decided to drill an 8" well into the cobble in order that
test pumping could be undertaken for drainage relief. On
April 15, 1947 a pump test was conducted by the SCS personnel,
Pumping at the rate of 100 gpm had only very local effects,
thereby indicating the need for a larger pump and certain
well improvements. The possibility of pump drainage was
clearly evident and aroused local support for a more detailed
study. In 1948, an agreement with the Drainage District and
the Soil Conservation District was formalized which initiated
a test program in the area. After considerable piezometer
analysis and topographic investigations were completed, a
well was installed by the Colorado Water Well Company in
October 1951 (4). Both the well construction and the
drillers' log of the material are shown in Fig. 10. The
well was pumped at a rate just exceeding 200 gpm for a per-
iod of about four years. The conclusions reached from this
study include:
(1) Analysis of the piezometer data indicated that the pump
produced a decline in the water table near the well of
46
-------
Drainage Well
Construction
Drillers Well Log
r-Vrrn
12" Spiral Welded
Steel Pipe 7ga.
25'
Well
1/8"
Brass
Screen
Openings
Clays,
Sandy Clay,
a
Silty Clay
Cobbles
Gravel
Sand
Shale
Depth, Ft.
I- 0
- 20
-30
-40
- 50
L-60
Fig. 10.
Construction and driller's log of 1951 test well
for pump drainage (4).
47
-------
approximately 0.10 inch per day, which decreased to 0.03
inch per day at a radius of about 1/2 mile.
(2) It was observed that the pumping produced greater and
more rapid changes in the aquifer pressure. The fact that
the dense clay layer overlying the cobble restricted flow
into the cobble from the soil was stated as the reason for
the relative slow effect on the water table.
(3) When the pump test was conducted/ it was noted that a
"hole" in the clay layer existed in the radius of the influ-
ence of the pump. It was through this hole that the water
above the cobble entered the aquifer. Consequently, a
drainage well in any part of the lower valley can be success-
ful only if openings exist in the upper confining stratum
which will allow the ground water above to enter the aquifer.
In order to evaluate the effectiveness of natural internal
drainage of the area surrounding the well, 27 locations
were studied for hydraulic gradient and hydraulic conductiv-
ity of the soil strata. The results of the composite tests
indicate that only 2.72 acre-inches per month could be hand-
led by natural drainage.
Canal and Lateral Seepage
A complementary investigation to drainage is an evaluation
of the sources of the excess ground water. Several studies
have been conducted in the valley starting in 1954. The
first study was a cooperative enterprise between the Colo-
rado Agricultural Experiment Station and the Agricultural
Research Service, U.S.D.A. (4). An eight-mile length of the
Grand Valley Main Line Canal was isolated. Both inflow-
outflow and seepage meter measurements were taken. The
results indicate an average loss rate in the section of
about 2 acre-feet per day per mile of canal (0.30 cfd) .
Later, on July 12, 1955, A. R. Robinson (25) conducted a
similar seepage loss investigation on the Government High-
line Canal, but little is known of the results. In 1958,
Solomonson and Frasier investigated lateral seepage on sev-
eral 200-foot sections (9). These tests utilized the pond-
ing method of analysis and indicated a loss rate of 0.40
acre-inch/day/mile. Summarizing the results of these
studies:
(1) Seepage rates in the canal were significantly higher
where the canals were located in the alluvium material. In
the shale cuts, the seepage rates were noticeably lower,
probably owing to quantities of ground water interception.
48
-------
(2) Results show that an average of about 5 acre-feet per
month per mile of canal through the test area would alone
exceed the internal drainage capacity of the soils.
Farm Efficiency
The conclusion has been reached by most investigators in
the area that excess applications of irrigation water are
the primary cause of the drainage problem in the lower
valley. To quantify the magnitude of these contributions,
efficiency studies were conducted in 1954 and 1955 by the
Colorado Agricultural Experiment Station (4), and by the
U.S. Bureau of Reclamation (34) . The earlier studies det-
ermined that an average of 7.4 acre-inches excess was being
applied seasonally, but the farms were located in a small
area. In order to provide more reliable data and to pro-
vide a basis for extending the results to the valley, the
1955 study involved six new farms between Grand Junction and
Fruita, which were supplied by the Government Highline Canal
and the Grand Valley Canal. The results of this study indi-
cated a significant amount (as high as 23.7 acre-inches per
acre annually) was being applied in addition to consumptive
use and leaching requirements. The Bureau of Reclamation
study was conducted from 1965 through 1968 on three locally
operated farms about 10 miles west of Grand Junction. Care-
ful consideration was given to the parameters affecting the
farm efficiencies being attained, as well as the efficiencies
that could be attained. The fields ranged in slope from 0.7
to 1.5 percent, and in length of irrigation runs, from 250 to
1252 feet. In addition, all three operators practiced diff-
erent farming methods to some extent, which gave the invest-
igators an opportunity to observe the effect of farming
methods on irrigation efficiency. The summary of the res-
ults, given in Table 11, indicated the following general
conclusions:
(1) The nature of irrigation in the area in the early part
of the season is not conducive to efficient irrigation as
the process of "wetting across," or getting the seed bed
properly moistened between furrows requires larger furrow
streams and long run periods.
(2) Careful observation of efficient water use not only
significantly improved yields, but also required less fer-
tilizer.
(3) Control of the Western Cutworm in sugar beet fields by
keeping a moist soil is seen to decrease efficiency. Since
drainage was not a problem in the area, this practice was
common and economical.
49
-------
Table 11. Overall seasonal irrigation efficiency percentages,
weighted by field acres (34).
Year Data Category Farm 1 Farm 2 Farm 3 Total
Measured
1965
NO.
NO.
NO.
1
2
3
Attainable1
Attainable2
Attainable3
Measured
1966
NO.
NO.
NO.
1
2
3
Attainable
Attainable
Attainable
Measured
1967
NO.
NO.
NO.
1
2
3
Attainable
Attainable
Attainable
Measured
1968
NO.
NO.
NO.
1
2
3
Attainable
Attainable
Attainable
Measured
Avg.
NO.
NO.
NO.
1
2
3
Attainable
Attainable
Attainable
33
60
68
71
28
57
67
70
24
57
66
28
55
65
28
57
66
71
.7
.5
.5
.8
.1
.0
.0
.4
.2
.0
.3
.1
.2
.2
.3
.3
.8
.1
40
56
63
72
38
55
62
68
36
54
63
67
26
51
59
66
33
56
64
68
.2
.8
.9
.3
.7
.8
.7
.7
.3
.9
.1
.1
.2
.6
.8
.9
.8
.4
.0
.8
42
69
53
61
67
33
57
63
41
63
65
.5
.6
.5
.6
.4
.2
.3
.8
.3
.1
.5
35
59
66
72
34
60
65
69
32
58
65
67
29
54
63
66
32
58
65
69
.6
.0
.6
.1
.6
.4
.3
.2
.7
.0
.9
.1
.0
.9
.4
.9
.6
.2
.4
.3
1
Attainable water use efficiency with existing system and
improved management (no additional labor).
2
Same as except with additional labor.
3
Same as 2 except with additional system costs.
50
-------
(4) Consideration of such factors as leaching and salt
loads during critical growth periods, as well as soil tilth,
not only improved yields, but also affected irrigation effi-
ciency.
Irrigation Methods
Because the saline soils have always been a problem, attempts
have been made to study certain alternative irrigation meth-
ods to determine their effect upon crop production. Sprink-
ler irrigation has usually been immediately abandoned because
of the crusting characteristics of the soil, as well as the
cost of such systems. During the 1954 irrigation season,
personnel of the Colorado Agricultural Experiment Station
conducted infiltration studies. The results are listed in
Table 12 (5). The reported infiltration rates are averages
over a time period of 10 hours, or more. Since infiltration
rate curves are not available for these same soils, inter-
pretation of the reported data is quite difficult. For
example, a low infiltration rate listed in Table 12 may only
indicate that water was being applied at a rate less than the
infiltration capacity of the soil. Also, the net irrigation
(inflow minus outflow) does not show the influence of furrow
stream size upon infiltration characteristics. In general,
at least two inches of water could be infiltrated into the
soil in a 12-hour period.
Salinity Constituents
The high clay and silt content of the local soils is greatly
affected by the types of salts present. It has been estab-
lished that calcium salts, for example, although not desir-
able in large quantities, tend to coagulate dispersed soil
particles, thereby increasing the permeability of the soil
and enhancing the leaching process. In contrast, sodium
disperses soil particles, thereby reducing the permeability,
which further reduces the drainage capacity of the soil.
Consequently, it is necessary to evaluate the amount of
sodium present in the soil to make judgments on drainage
design and the potential for alleviating the general detri-
mental effects of the salts. The studies reported earlier
by the Colorado Agricultural Experiment Station considered
this problem by evaluating the "exchangeable sodium percent-
age." Table 13 summarizes portions of the 1952-55 studies
(30). In a later section, this analysis will be extended to
river water, soils, ground water, and irrigation return flows
to determine the net contribution by the whole valley.
51
-------
Table 12. Results of 1954 infiltration study (4).
Date2
6-14,15,16
7-8,9 10
7-23,24 25
8-3,4,5
8-23,24,25
9-20,21,22
5-17,18
6-22,23,24
7-12,14,15
7-26,27,28
6-4,5,7
6-25,26,27
7-29,30,31
5-27,28
6-3
6-28,29,30
7-19,20,21
North Repl.
Net
Irrig. Time Rate^
in.3 hr. in./hr.
Middle Repl.
Net
Irrig. Time Rate1
Inches hr, in./nr.
South Repl.
Net
Irrig, Time Rate1
Inches hr. in,/hr.
SUGAR BEETS, -Plots (3 ,7 , 22) (8 ,10 ,25) (16,29 ,32)
3.26 10 ~ 0.326
2.10 11 0.1.91
2.59 11 0.235
2.69 11- 0.245
3.04 12 0.253
4.23 12 0.353
3.28 10 0.328
3. .03 11.25 0.269
2,08 11 0.189
2.44 10 0.244
3.20 12 0.266
3.72 13 0.286
3.56 10 0.356
3.04 11 0.276
3.15 18 0.175
1.45 19 0.076
3.05 12 0,254
2.99 14 0.214
CORN, Plots (2,4,20) (9,24,27) (14,30,33)
3.39 34 0.099
2.80 11 0.254
2.78 12 0.232
2.53 17 0.148
6.97 45 0-.154
3.04 11 0.276
2.03 23 0.088
2.14 16 0.134
6.09 44 0.138
3.77 11 0.343
1.64 12 0,136
2.55 19 0.134
BARLEY, Plots (5,21) (12,26) (18,31)
4.11 23.5 0,175
3,24 12 0.270
4.08 12 0.340
0.45 22 0.020
2.36 11 0.21
3.16 12 0.263
0.82 13 0.063
2.43 17 0.142
4.24 13 0.326
ALFALFA, Plots (1,6,19) (11,13,23) (15,17,28)
1.79 16 0.111
6.12 23 0.266
6.07 23 0.264
5.60 23 0.243
5.20 22 0.236
5.17 23 0,225
3.47 23 0.151
4.76 23 0.206
4.72 23 0.205
Infiltration.rate used is the net irrigation divided by the total time.
Records up to June are in general of no value because irrigation was not done by
replicates.
Inflow minus outflow.
-------
Table 13. Results of 1952-1955 field leachinq study showing effect on
exchangeable sodium percentage.
Ui
00
Treat- Sampling
ment1 Date2
0-9
W1G1
W1G2
W2G1
W2G2
W, (Mean,
Xall
plots)
W,(Mean,
all
plots)
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
11
5
6
6
6
7
4
5
5
5
8
3
4
5
5
9
3
5
5
6
9
4
6
5
6
8
3
5
5
6
.46
.23
.80
.21
.44
.47
.61
.77
.01
.96
.25
.40
.86
.37
.75
.45
.76
.31
.36
.46
.47
.92
.29
.61
.20
.85
.58
.09
.36
.11
EXCHANGEABLE SODIUM PERCENTAGE
Soil depth - inches
9-18 18-30 30-48 48-60 60-72
10.74
6.61
11.33
9.32
10.98
13.84
6.21
8.81
8.35
9.56
9.95
4.69
6.09
5.29
6.53
13.69
4.48
4.73
5.22
6.78
12.29
6.41
10.07
8.84
10.27
11.82
4.59
5.41
5.26
6.66
10.69
12.38
19.54
16.28
12.60
23.30
10.67
14.09
15.61
18.00
14.08
4.89
6.89
6.76
9.76
18.52
5.06
6.65
6.01
8.68
17.00
11.53
16.81
15.95
15.30
16.30
4.98
6.77
6.39
9.22
11.01
15.98
25.38
18.74
16.59
25.67
16.. 89
19.50
21.64
24.07
18.80
8.11
11.00
11.72
15.81
18.49
8.94
15.59
15.60
19.73
18.34
16.44
22.44
20.29
20.33
18.65
8.53
13.30
13.66
17.77
23.89
18.33
24.11
22.53
17.72
23.25
15.18
23.35
24.00
20.43
16.45
23.30
23.66
21.54
21.35
21.95
22.60
21.65
72-84
21.10
22.63
19.03
21.01
21.87
20.02
84-96
17.95
18.49
19.59
19.18
18.22
19.39
Alfalfa
yield
Tons/Ac
4.01
3.44
2.19
4.72
4.18
2.73
5.30
5.01
3.18
5.00
5.01
3.00
4.37
3.81
2.46
5.15
5.01
3.09
1 Reclamation treatments, 1952-53
W, - Leaching with 2 acre-feet of water/acre
W, - Leaching with 6 acre-feet of water/acre
G, - No gypsum
G, - Gypsum, 4 tons/acre
2Samp'ling dates:
1 - Before reclamation, May, 1952
2 - After reclamation, August, 1953
3 -'After 1 crop year, September, 1954
4 - After 2 crop years, September, 1955
5 - After 3 crop years, October, 1956
-------
Regional Hydrologic and Salinity Studies
The increasing salinity problem in the Colorado River Basin
has necessitated the collection and analysis of data on water
and salt flows in order to evaluate the contributions from
various sources. Although several interested governmental
agencies have conducted short term studies in the basin, the
primary source of data is the stream monitoring system of the
U.S. Geological Survey. One of the most comprehensive
efforts to summarize and analyze these data was made by
lorns, Hembree, and Oakland (16) for the period between 1914
and 1957 and adjusted to the 1957 conditions. The study was
inclusive of the entire Upper Colorado River Basin, but for
the purposes of this report only the section dealing with
the Grand Valley area has been extracted. Because of the
location of the exiting gaging station being below the con-
fluence with the Delores River, some of the data are not
uniquely representative of the Grand Valley.
Some of the results of this study provide an interesting
overview of the basin-wide implications caused by water use
in the Grand Valley. An extraction of part of the data is
shown schematically in Fig. 11, showing the fraction of
water and salt that flow in the Grand Valley in proportion
to the water and salt flows at Lee's Ferry, Arizona. The
effect caused by water resource development in the basin
upstream from the Grand Valley was shown to be an increase
from 178 to 592 ppm in the Gunnison River Basin and from
272-387 ppm above Grand Valley along the main stream. The
net effects of man's activities through the Grand Valley
were determined to be a salinity increase from 256 to 547
ppm. The total salt loading to the Colorado River from
the Grand Valley averaged about 750,000 tons during the
period, although when adjusted to the 1957 conditions, the
value was set at 440,600 tons. In terms of tonnage contri-
bution per acre, the figure would be between 5 or 6 and 8
tons per acre, depending on the time period used.
The wide fluctuation in salt pickup through the Grand Valley
is shown in the report by lorns, et. al to be related to
the river discharge. For example, during the period from
about 1930 to 1942, the average was 860,000 tons pickup per
year, in 1943 to 1951 the average pickup was 745,000 tons/
year, and in the 1951-1957 period the addition was only
490,000 tons/year. The significance of this variation in
salt pickup is that during each of these time periods, the
annual river discharge was decreasing, which would indicate
that during water short years the farm efficiency increased
or ground water storage increased, thereby resulting in
dramatic salinity control circumstances.
54
-------
Percentage of Combined Flow
of Colorado River at
Lee's Ferry Arizona
Percentage of Combined Dissolved
Solids Discharge of Colorado River
of Lee's Ferry, Arizona
Gunnison River near Grand Junction, Co!o._
Plateau Creek near
Cameo, Colo.
Utah Stale Line
23.54 \Coiorado River near
18.19 / Cameo, Colorado
Colorado River at Colo.-
Weighted Average Dissolved
Solids Conentration in ppm
'\ Grand Valiey
Grand Junction, Colorado
Fic 11. Water and salt flow diagram in the Grand Valley based
on 1914-57 data adjusted to 1957 condxtions.
55
-------
The 1963-1967 water years were selected by the Colorado
River Board of California (7) in conjunction with various
governmental agencies to appraise the salinity sources in
the basin and to evaluate the future impact of water res-
ource developments on mineral water quality. The results
pertaining to the Grand Valley in particular indicated the
salt pickup to be about 8 tons per acre per year, which is
the results Hyatt (14) established for the 1963-1968 years
(Fig. 12). Both of these references are useful data sources
for examination of the Upper Colorado River System. Also,
both studies utilized salinity data collected by the Federal
Water Pollution Control Administration (now the U.S. Environ-
mental Protection Agency).
Two additional references, not directly related to salinity
studies but helpful sources of information, are listed as
references (7) and (18).
56
-------
River Outflows
4,444,000 ac-ft
GroundWater Outflows
I05.00O ac-ft
\
Phreatophyte Use
75,000 ac-ft
Agricultural Use
185,000 ac-ft
River Inflows
4,690,000 ac-ft
^Tributary Inflow
40,000 ac-fc
Precipitation
75,000 ac-ft
River Outflows
3,907,000 tons
Ground Water Outflows
295,000 tons
Natural Sources
70O.OOO tons
Agriculture
265,000 tons
River Inflows
3,180,000 tons
Tributary Inflow
57,000 tons
Fig. 12. Schematic water and salt budget for the Grand Valley
during 1963-64 water years (14).
57
-------
SECTION VI
GRAND VALLEY HYDRO-SALINITY SYSTEM
The preparation of water and salt budgets requires a quan-
titative description of the pertinent segments of the res-
pective flow systems. Even though the emphasis of this
study is in the small intensive study area, Area I, the
examination of the system on a valley wide scale allows
a better understanding of the regional characteristics
and thus permits a more reasonable basis for generating
conclusions.
In undertaking the Grand Valley Salinity Control Demonstra-
tion Project, one of the first tasks was to conceptualize
a hydro-salinity model of the intensive study area. This
model had to have sufficient sensitivity to detect the
effects of canal lining upon the salt pickup reaching the
Colorado River. Then, the model could be used to design
the field data collection system. Finally, the model could
be used to extrapolate results from the intensive study
area to the entire Grand Valley.
A difficulty often encountered while preparing water and
salt budgets is the variability in the accuracy and relia-
bility with which the hydrologic and salinity parameters
are measured. Usually, the measurement precision varies
with the scope of the research and the area of the study.
The intensive study area on this project has been observed
in great detail as will be shown in a later section, but
the description of the valley itself is based primarily
on the work of others and thus is more generalized.
Because of these circumstances, it is helpful in the
understanding of investigation results if the techniques
employed in computing the budgets and the simplifying
assumptions which are made are examined.
Since the hydrologic system is difficult to monitor and
predict, it is impractical to expect their models to oper-
ate without applying some adjustments in order that all
components will be in balance. In short, the budgeting
procedure is usually the adjustment of the segments in the
water and salt flows according to a weighting of the most
reliable data until all parameters represent the closest
approximation of the area that can be achieved with the
input data being used. The vast and lengthy computation
procedure of calculating budgets is facilitated by a math-
ematical model programmed for a digital computer. A com-
plete listing and explanation of its operation has been
59
-------
previously reported (38) . For the purposes of this report,
the more important aspects will be extracted for discussion.
A schematic diagram of a general hydro-salinity model is
shown in Fig. 13.
The hydro-salinity system of the Grand Valley can be divided
into four general areas:
(1) Inflows. Inflows represent the total water potentially
available for use within the area and the dissolved minerals
carried by this water. Included in this group are river,
tributary, and ground water inflows, importations, and pre-
cipitation.
(2) Cropland diversions. From the available supply of
water (river inflows) coming into the valley, diversions are
made into canals. From the main supply canals, small turn-
out structures are used to divert the water into small
lateral ditches which lead to the fields.
(3) Ground water. Water that is applied to the land in the
form of precipitation or irrigation may be either transpired
by the crops or lost through deep percolation into the
ground Water flow system.
(4) Outflows. Once having been used, the water returns to
the river system or is lost to the atmosphere through evapo-
transpiration. Numerous routes are taken by the water to
reach'the river including surface drainage and ground water
return flows.
In the following sections, the aspects of these divisions are
explored.
Inflows
River Inflows
The exclusive sources of irrigation water in the Grand Valley
are the Colorado and Gunnison Rivers. Together, the two
rivers represent an annual average combined flow of 6500 cfs
from which large check type structures are used to divert
the water into the principal supply canals. Owing to the
increased development of the water resources in the Upper
Colorado River Basin, the discharges in the rivers in the
Grand Valley region are highly affected both in terms of
volume and flow rate by transbasin diversions to Colorado's
Frontal Range, reservoirs, power development and irriga-
tion. The Colorado River, at the east entrance to the valley.
60
-------
\A/nt
<^nlf
Flows
Flows
River
Inflows
1 1
' 1
1
Ev
*
Canal
Seepage
r~
1
1
1
1
1
J
Canal
aporation Diversions
t '
i
r ~t
Lateral
Diversions Spillage
f
Latera
Seepage
r
L
<— •
1
*
Deep
Percolation
G
\
<
i
iround
Voter
Storage
I
Ground Water
Outflows
1 i
L
J .,
- 1
-
r
Root Zone Field
Supply Tailwater
i
i
| I
' \
i
- -*• 1
L-
Consumptive Soil Moisture
Use Storage
ij— & — '
* *v2/* -|
r i
Dra
Ret i
nage
jrn Flows |~
J
[
i
r
-•-,
i _
i
t
Tributary
Inflows
i
i
Ground Water
Inflows
I
I
1 mports
1
i
1
Free potation
*
Phneatophyte
Consumption
i
* t
Exports
i
1
River
Outflows
t t
Municipal
- Uses
Fig. 13. Schematic diagram of generalized hydro-salinity model.
61
-------
drains an area of about 8,050 square miles resulting in an
annual average discharge of about 4000 cfs. Dissolved sol-
ids concentrations at the station, "Colorado River near
Cameo," range from 150 to 1000 ppm, with the annual flow-
weighted mean between 300 and 400 ppm. Salinity levels
fluctuate seasonally with peak concentrations occurring
during the low flow months of the year, usually December
and January. The river at this point also carries large
sediment loads, especially during the high flow periods in
the spring, which aids irrigation in the valley by reducing
intake rates during the early growing season when smaller
irrigations suffice. The effect of development upstream
of Grand Valley is clearly noticeable, as has been previ-
ously indicated. A large part of these conditions are
related to the approximately 190,000 irrigated acres which
deplete about 190,000 acre-feet of water annually from the
river system (7). The Gunnison River Basin, while about
the same size, uses about 350,000 acre-feet annually on
about 270,000 acres. The resulting annual flow at Grand
Valley is reduced to about 2500 cfs, but contains between
500 and 600 ppm of salts. The variation in salinity of
waters diverted for irrigation range from 150 to 3,000 ppm,
with a few measurements of 6,000 ppm. These higher values
of salinity usually occur in the Fall months for waters
diverted from the Gunnison River. Also, the waters diverted
from the Gunnison River are used in the Redlands area, which
is located south of the Colorado River and west of Grand
Junction. The alluvial soils in this area facilitate drain-
age so that local salinity damage is not prevalent. The
lands north of the Colorado River use irrigation waters
having a maximum salinity of 1000 ppm.
Tributary Inflows
Tributary inflows, which are the ungaged water resulting
from precipitation on the adjacent area in the valley,
actually account for only a minor portion of the water
passing through Grand Valley. Aside from the 60,000 acre-
feet added by Plateau Creek, the estimated yield from the
surrounding watershed is only about 55,000 acre-feet (7),
(14), (16). As noted earlier, the precipitation averages
about 8 to 9 inches per year and the intensity is usually
low enough to allow the soils to store most of the water.
The area is marked by natural washes, evidence that some
periods of tributary inflows occur, but for the majority
of the time, the flows in these washes are field tailwater
and drainage return flows.
62
-------
Imports
Importation of water from nearby mountain watersheds currently
supplies the bulk of domestic demands in the valley although
new treatment facilities have been built to use water from the
Colorado River. In addition, several deep wells are used to
supply some domestic and commercial water demands. None of
this water is used for irrigation as a rule because of the
abundance of river water.
Ground Water Inflows
Ground water inflows to the valley are essentially impossible
to measure, but should be accounted for in the water and salt
budgets. Hyatt (14), using an electronic analog computer
system model of the Grand Valley, indicated little or no
ground water inflows to the region. His conclusion seemed
well justified as both the rivers enter the valley through
rocky mountainous channels.
Cropland Diversions
Canal Diversions
The source of the irrigation water supply is the diversion
into canals by means of check-type diversion dams. Distribu-
tion of the canal flows occurs in four ways: (1) diversions
into the farm lateral system; (2) seepage; (3) spillage into
wasteways; and (4) evaporation.
By using the natural washes as wasteways, the individual
canal companies maintain regulation points along the system
where control of downstream flows can be made. This practice
has the advantage of affording ready compensation for drastic
events such as irrigation cutbacks due to foul weather or
increased demands by periods of warmer weather. Even though
this practice is not a desirable water management alternative,
the long length between canal headworks and the end of the
distribution system, along with the abundance of water, make
spillage the most employed regulation tool in Grand Valley.
One situation does exist where spillage is used to supply
another segment of the system. The Grand Valley Canal spills
water into what is known as Lewis Wash, in the study area,
which is then diverted by the Mesa County Ditch. A notice-
able consequence of this particular operation is the poorer
quality of irrigation water being used by irrigators served
by the Mesa County Ditch resulting from mixing the spillage
with the drainage waters in Lewis Wash. The salinity being
63
-------
added to the spilled water throughout the valley is difficult
to determine, but in the course back to the river system,
evaporation and phreatophyte consumption further concentrate
existing salt concentrations.
Seepage from the conveyance channels enters the ground water
basin directly and, in the Grand Valley, these flows compli-
cate an already serious drainage problem. Most estimates of
the magnitude of the seepage losses range in the neighborhood
of 20%, but considerable variability has been noted. For
example, studies by different researchers have indicated that
seepage along canal sections built through the alluvial soil
are much higher than those in which the channel had been cut
through the shale formations.
Lateral Diversions
The term lateral as used in this text refers to those small
conveyance channels that deliver water from the company oper-
ated canals to the farmers' fields. These small conveyance
channels usually carry flows less than 5 cfs, and range in
size up to 4 or 5 feet of wetted perimeter. During the
early part of this project, the lateral system in the Grand
Valley was assumed to have about the same impact on the
overall system as did the canals. Later efforts showed that
the lateral system in the valley is so immense in total
length as compared with the canal system that this assump-
tion was wrong. In order to demonstrate the extensive magni-
tude of the lateral distribution, studies were conducted by
project personnel to establish the extensiveness of the
system. In each different region of Grand Valley, sections
(640 acres) were surveyed to establish the lengths of lined
and unlined laterals, as well as determining the need for
additional water control structures, so that analysis
regarding the effect of laterals upon salinity control could
be made. A summary of this work has been included in Table
14 at this point in the report, even though a more detailed
discussion will follow in a later section of this report.
In a manner similar to the distribution of canal discharges,
lateral diversions may be divided into four classes: (1)
diversions reaching the crop root zone; (2) flows that are
allowed to run off the ends of the fields during irrigation,
otherwise known as field tailwater; (3) seepage losses; and
(4) evaporation from the water surfaces. The nature of
irrigation practices in the region is not conducive to effi-
cient handling of water in the laterals due to their tremen-
dous lengths. Other factors influencing water management
methods include the slope of the land, which is about 50 feet
per mile in some places, and the inexpensive water supply.
64
-------
Table 14. Results of lateral survey.
Location
Township
T1S, R1E
T1S, R2E
T1S, R1W
T11S, R101W
T2N, R2W
TIN, R2W
Sec
2
3
4
9
10
11
15
16
17
20
28
9
7
22
35
3
11
15
23
Lateral Lengths (ft)
Farm
Unlined
10,560
36,990
4,600
4,570
31,840
4,920
36,040
29,020
34,620
25,750
48,640
22,280
12,830
22,700
15,580
4,750
3,700
28,510
17 ,210
Farm
Lined
500
4,350
10,060
6,570
8,160
1,520
640
9,970
12,300
8,450
2,290
18,900
4,230
12,140
1,320
3,780
Supply
Unlined
7,930
9,074
7,500
26,370
23,330
8,340
28,310
7,470
15,640
5,020
6,440
9,130
7,130
15,310
23,760
30,360
3,960
Supply
Lined
1,060
7,950
1,060
480
4,780
680
6,040
6,960
1,600
4,880
14,410
1,920
7,500
14,260
13,200
16,370
5,540
21,500
Ave
Discharge
(cfs)
0.75
2.0
0.75
1.60
1.50
0.5
2.50
1.00
2.50
1.00
1.25
0.75
0.50
0.75
2.5
2.5
2.5
2.0
2.5
_ltl_
-If"
(each)
4
1
2
4
5
2
7
5
1
3
3
2
2
3
-itr
(each)
7
23
3
3
37
3
42
32
36
22
28
18
11
5
12
12
8
21
19
(eachT
24
72
11
14
106
11
107
82
87
47
74
61
36
34
33
31
26
52
47
fiP
(each)
1
1
1
3
1
11
en
Ul
*Measuring flume
-------
Numerous instances exist where the water in laterals flows
continuously, with the water not used for irrigation being
dumped into the surface drainage system. A preliminary
sampling of these discharges indicated some salt pickup
from the soil surfaces, as well as concentrating the salt
due to evaporation from water surfaces.
Root Zone Water
The purpose of irrigation is to supply the crop root zone
with sufficient water to meet the evapotranspiration demands.
During the process of crop water use, the dissolved minerals
in the water are isolated, resulting in accumulations
occurring in the root zone. This situation necessitates a
leaching of these salts by an additional quantity of water.
There are often difficulties in irrigating farm lands because
of the relative effects of water on the plants. For example,
when insufficient moisture is provided during critical
growth periods, the reduction in yield may be enormous. In
most situations, a small excess produced very little damage,
resulting in a tendency to over-irrigate. The consequences
of over-irrigation are unnecessary fertilizer leaching, high
water tables and drainage requirements, and large salt addi-
tions to the river systems.
Water moving into the root zone is either lost to the atmos-
phere through evapotranspiration, or lost through deep per-
colation below the root zone, or it may be stored within
the root zone. The delineation of these flows by measure-
ment is extremely difficult and impractical on a large scale.
Consequently, the procedure most often used is empirical
computational methods .
Numerous methods of estimating evapotranspiration have been
developed for agricultural lands. Probably the two most
adaptable methods for the semi-arid western regions are the
Blaney-Criddle method (3) and the Jensen-Haise method (17) .
The Blaney-Criddle method involves the determination of
consumptive use as a function of mean monthly temperature
and the percentage of daylight hours occurring during the
month. The general equation can be expressed as,
U= (t-p/100) • (K-K) • (A)/12 ........... (1)
Where U is the water use in acre-feet, t is the mean monthly
temperature in degrees Fahrenheit, p is the yearly daylight
hour percentage occurring during a month, KC is the crop
growth stage coefficient determined experimentally for each
individual crop, A is the acreage of a particular crop or
66
-------
phreatophyte, and K is a climatic coefficient expressed as
Kfc = 0.0173-t - 0.314 ............ (2)
The Jensen-Haise method was formulated from the evaluation
of about 3,000 published and unpublished reports on short
period measurements of evapotranspiration using soil sampl-
ing procedures during a 35-year interval in the western USA.
The resulting equation is,
ET = Kc Etp
in which ET is the evpotranspiration, K is a crop coeffi-
cient much like the Blaney-Criddle Kc value, and Etp is the
potential evapotranspiration in a well watered soil in a
semi-arid area. The value of Etp is computed by a relation-
ship between air temperature and solar radiation,
E = (0.014t - 0.37) • R ....... (4)
JL
where t is the temperature in degrees Fahrenheit and R is
the solar radiation in Langleys. s
In order to determine the magnitude of deep percolation
losses and root zone storage, some simplifying assumptions
must be made. Since vegetation is only capable of trans-
piring at its potential rate when soil moisture storage
is adequate, an adjustment based on the storage and irriga-
tion supply whenever insufficient water is available must
be made to the potential value . The measured values of
canal and lateral diversions do not reflect the application
on each field or each crop and so the assumption has been
made that the irrigation is made uniformly over the cropland,
Thus, the water used from the root zone would only involve
crop requirements , and phreatophyte use was assumed to be
from the moisture below the water tables. Evaluation of
reported crop and soil characteristics in the area can be
made to determine root zone depths and soil moisture storage
capacity as they change with time (3, 11, 17, 24, 31). Once
these parameters have been established for an area, a budget
of root zone water can be made . The calculated total poten-
tial consumptive use is first compared with the total water
added to the root zone from irrigation and precipitation.
Three alternatives are assumed:
(1) If the supply to the root zone is less than the poten-
tial demand, but ample water is stored within the root zone
to meet the deficit, then the use would be equal to the
potential demand. Since the usual budgeting procedure is
carried out on a monthly time interval, the next period of
study would have an unused root zone storage that would be
filled or supplemented with that period's supply. It has
67
-------
been assumed that whenever a deficit in root zone storage
exists, no water is lost to deep percolation.
(2) If the sum of the supply and the available storage is
less than the potential demand, the actual use is assumed to
be the total quantity available. A term called consumptive
use deficit is defined as the difference between potential
demand and the actual use. Again, there would be no deep
percolation loss.
(3) If the supply to the root zone is sufficient to meet
the potential demand, the actual use would equal this demand
If the excess is sufficient to refill the soil moisture
storage, the deep percolation loss would be that amount of
water greater than is necessary to refill the soil moisture
storage to field capacity.
An illustrative flow chart of this routine is shown in Fig.
14.
Ground Water
The discussion of ground water in this section is limited
to the area below the water table as the root zone discussion
of the preceding section involved the region above the
water table. Ground water recharge in the agricultural reg-
ion is comprised of canal and lateral seepage as well as
deep percolation of applied irrigation water. The hydraulic
gradient resulting from the recharge causes the movement of
water towards and into the river system.
Ground water discharges involve two phases: (1) drainage
interception; and (2) subsurface outflows. Since the water
table is often intersected by the drainage system, these
flows are easily measured by flow measuring devices located
in these drains. The subsurface outflows cannot be measured,
but with water table elevation data throughout the area,
along with hydraulic conductivity measurements in the vari-
ous subsurface strata, these flows can be reasonably computed
Even though considerable effort can be made to monitor the
pertinent subsurface variables, the data usually obtained
do not warrant a non-steady state analysis unless a ground
water study is the specific objective of a project. For the
purposes of this study, Darcy's steady state equation has
been used (19):
Q = AK(dh/dx) (5)
in which Q is the discharge, A is the cross-sectional area
of the ground water flow, K is the hydraulic conductivity,
and dh/dx is the hydraulic gradient in the direction of flow.
68
-------
All Other
Land Uses
is
Area of
Cropland=0?
USE=OH
-HUSE=PREC
USE=RZS+RZST
1
CUD=PCU-USE
i
IIS
(RZS-PCM)>
IRZC-RZST)?
0,RZST=
AGW*0
RZST=RZC
[ AGW=(RZS-PCU)-(RZC-RZST)
AGW=O
Rz$T=RZST+(Rzs-pgi)
IS
Area of
Land Used?
USEXTJ—|
USE=PREC-
Fig. 14,
PCU= Potential Consumptive Use
PREC= Precipitation
RZC= Root Zone Capacity
RZSC= Root Zone Storage
CUD= Consumption Use Deficit
AGW= Additions to Ground Water
Illustrative flow chart of root zone budgeting pro-
cedure .
69
-------
During the course of the investigation, it was felt that the
weakest link in the data was in determining the values of
hydraulic conductivity. However, it seemed reasonable to
assume that the relative magnitude of conductivity between
one strata and another could be determined with reasonable
accuracy. With this type of data, it is possible to formul-
ate two independent methods of calculating the ground water
flows and thus to increase the accuracy of the hydrologic
budgeting procedure by forcing an alignment between the two
methods.
The ground water analysis illustrated in Fig. 15 involves
the comparison of the ground water outflow based on a mass
balance arrived at through a general budgeting procedure
(inflow minus outflow equals storage changes) , where compu-
tations of outflows are based upon measured hydraulic grad-
ients and conductivity data. Because the model only uses
relative magnitudes of strata hydraulic conductivity, the
values are adjusted based upon their relative proportion
until each value of monthly ground water outflow is consis-
tent between analyses. Then, the variability of the com-
puted values of hydraulic conductivity are examined. If they
are homogenous, the model represents the "best fit" between
all monitored data. The computation of ground water outflow
based on Darcy's equation for a number of strata can be
written:
where A^ is the area of the nth strata, K^ is the hydraulic
conductivity of the n^ strata, and dhn/dxn is the hydraulic
gradient acting on the nth strata. Occasionally when no
confining layers exist, the hydraulic gradients would be the
same for each strata; however, in the Grand Valley an under-
lying cobble aquifer is partially confined. The discharge
computed from Eq. 6 will generally not be comparable in
magnitude to the expected values determined from the mass
balance analysis for the following reasons:
(1) The measured values of conductivity can be in error and
in different units. Usually conductivity is determined in
in/hr while the ground water outflows will be in acre-feet/
month. To avoid confusion, these inconsistencies are compen
sated for in the adjustments.
(2) It is often difficult to evaluate the respective strata
areas accurately. Consequently, a representative thickness
can be determined and then a convenient unit width selected
for the computations. If this practice is used, the flows
will be altered, but the adjustment can be absorbed in the
adjustments to hydraulic conductivity.
70
-------
Start
I
nyarauuc
Grad ent
Initial
Ground
Water
Estimate
— •* T YRtievvi;
i
ZZi= 2YYj
t
c.ievvc;;/ UIST. |
' |GradJ=Ave.ZZj |
H/~l— X*DWr*: V A
\J— 2j<^->\ ^ "
CjXGradj]
1
*
I
Adjusted
Hydraulic
Conductivity
1
Final Ground
Water
Estimate
Comparison of
Homogeniety of
Hydraulic
Conductivity During
Water ^fear
-»JAQ=SAHC-, xGradiXAreai j
i = Refers to ith Strata
Grad. = Hydraulic Gradient
Q = Computed Ground Water Outflow
PHC =Field Values of Hydraulic Conductivity
AHC = Adjusted Values of Hydraulic Conductivity
TGWOF= Total Ground Water Outflow from Mass Balance Analysis
AQ =TGWOF
Fig. 15. Illustrative flow chart of ground water modeling
procedure.
71
-------
The adjustments to the field hydraulic conductivity measure-
ments can be made as indicated:
K.=(TGWOF • K!)/(value of discharge obtained from Eq, 6)..(7)
where K. is the adjusted hydraulic conductivity, TGWOF is the
ground water outflow estimate from the mass balance analyses,
and K! is the field measurement of hydraulic conductivity.
The salt flows in both the root zone and the ground water
flow systems are important items that will be discussed in a
later section.
In summary, the computational procedure for evaluating ground
water flows, which is also used in this study as a basis for
adjusting the complete hydrologic and salinity budgets, is
as follows:
(1) From field data collected on hydraulic gradients and
conductivities, along with physical dimensions of the system,
a value of ground water discharge can be computed using
Darcy's equation.
(2) Comparison of the values obtained in step (1) with the
estimates of ground water outflows based on a mass balance
analysis is used to adjust the field values of conductivity
according to their relative magnitude until both methods of
computing discharge agree.
(3) Compare the monthly values of adjusted hydraulic con-
ductivity for homogeniety. If the values are found to be in
error, all parameters in the hydro-salinity model are not
aligned and further adjustment of various budget factors is
necessary.
Outflows
The water leaving Grand Valley, aside from evapotranspiration,
includes the river outflows and ground water flows occurring
beneath the gaging station. Another common form of regional
outflow is exportation, but in Grand Valley none of these
exist.
River Outflows
The Colorado River exits from Grand Valley in the western end
with a mean annual discharge of about 6,500 cfs and a salt^
load of about 900 parts per million of total dissolved solids.
72
-------
The resulting salt pickup from Grand Valley during most
normal water years varies between 0.7 and 1.0 million tons.
Ground Water Outflows
The estimated discharge under the exit gaging station oper-
ated by the U.S. Geological Survey has been shown to be
small in comparison to the river flows (14). However, the
reliability of this type of an assessment should be ques-
tioned in light of the difficulty of monitoring the subsur-
face outflow without undertaking a ground water study, which
requires field drilling operations in order to provide the
necessary data for computing the discharge below the ground
surface.
Hydro-Salinity Model
The vast computational requirements requisite to formulat-
ing water and salt budgets, often called hydro-salinity
modeling, is best facilitated by digital computers, or as
in the case of Hyatt (14) by electric analog computing
systems. The results of this study were derived from a
digital program which has been reported previously (38).
It may be helpful in other studies to discuss the general
nature of the model program.
The mathematical model derived for this study attempted to
simulate the hydrologic conditions of the agricultural sys-
tem in Grand Valley, but the concepts are general and can
be extended with modification to other areas that are simi-
lar in nature. The program was written in individual but
interconnected subroutines that give the program a measure
of flexibility during operations by separating the calcula-
tion phase from either input or output phases. Thus, sev-
eral of the subroutines become optional if their functions
can be replaced by input data, or if certain outputs are
not desired. This general nature of the program is illus-
trated in the schematic flow chart shown in Fig. 16 with
name and functions tabulated in Table 15.
The main portion of the program is used to read necessary
input data and to control the order of water and salt bud-
get calculations. There are certain advantages in separat-
ing the input, output and computational stages of a program
including:
73
-------
( Start j
Main
Program
Subroutine
WATER
Subroutine
ACUS
Subroutine
GWMOD
Subroutine
PCUS
Subroutine
PCUO
Subroutine
CGSC
Subroutine
BUDO
Subroutine
GWMOP
Subroutine
SALT
Subroutine
SABU
Fig. 16. Schematic flow chart of hydro-salinity model
74
-------
Table 15. Hydro-salinity model subroutine descriptions.
Subroutine
Description
WATER
BUDO
PCUS
PCUO
CGSC
ACUS
GWMOD
GWMOP
SALT
SABU
Computation of monthly and annual values of the
water budget. Relatively little independent
data is generated by WATER directly since it
functions primarily as a summary.
Outputs data generated from WATER as the water
budget.
Computation of monthly and annual value of
potential consumptive use for irrigated crops,
dryland crops, municipal uses, industrial uses,
open water surfaces, and phreatophytes.
Outputs data generated in subroutine PCUS.
Outputs values of crop growth stage coefficients,
Computation of the estimated actual consumptive
use and the various root zone parameters.
Computation of the discharges through the ground
water model and adjusted strata hydraulic con-
ductivities. When these values of conductivity
approach equality, the ground water outflows are
correct.
Output of ground water model computations.
Computation of the salt budget for the area.
Output of salt budgets.
75
-------
(1) Input order is not important as the data are completely
available at all stages of computation.
(2) Variable sets of data can be utilized in the model when
several budgets are desired, or when some form of integration
is desired. This is especially useful when an area can be
broken down into smaller dependent areas.
(3) The functions of the subroutines are independent of
input, thereby making each subroutine a unit than can be
implemented in other programs.
(4) Corrections and adjustments are easily made without
detailed consideration to other segments of the program.
In controlling the computational order of the program, the
main program separates the calculation of the water and salt
budgets. Consequently, the modeling procedure involves only
the water phase of the flow system. This has been possible
in this study because of the detail in which data have been
collected. Once the water flow system has been simulated,
the individual flows are multiplied by measured salinity
concentrations and converted to units of tons per month. At
this point in the formation of the budgets, careful attention
must be given to the salt flow system since irregularities
may be present, thereby necessitating further model adjust-
ments. Thus, when the final budgets have been generated,
the salt system, ground water system, and surface flow system
must be reasonably coordinated and additional reliability is
assured.
76
-------
SECTION VII
FIELD INVESTIGATIONS METHODOLOGY
The evaluation of canal and lateral linings as feasible
salinity control measures depends to a large extent on the
success of isolating and measuring the various segments
comprising the water and salt flow systems discussed in the
previous section. The primary emphasis of the study took
place in Area I, the intensive study area shown in Fig. 6.
In the principal test area, the local effects of poor water
management including canal and lateral seepage were signifi-
cant. Hydrologic conditions could be studied in reasonable
detail. An additional advantage of this location was that
a majority of the irrigation companies in the valley would
be involved in the demonstration, thereby facilitating the
application of project results to other areas of the valley.
The smaller test locations, Areas II and III, were selected
to evaluate the effects of canal lining under different land
conditions. These areas involved additional irrigation com-
panies also.
In any investigation, a balance must be reached between the
physical size of the area, level of funding for the project,
and the detail with which the components of the system are
to be studied. The detail of this investigation was suffi-
cient to adequately meet the stated objective, as well as
provide considerable insight into the Grand Valley salinity
problem. The experimental design was comprised of two
phases: (1) instrumentation, and (2) peripheral investiga-
tions.
The instrumentation in the study area indicated by Fig. 17
provided valuable data concerning many of the important water
and salt movements. While some of the parameters were meas-
ured directly such as drainage discharges, lateral diver-
sions, water quality, and precipitation, others were invest-
igated indirectly. These budget parameters relate mostly to
ground water movement and were monitored for changes using
such techniques as piezometers, wells, and soil sample anal-
yses.
Because so many of the water and salt subsystems cannot be
evaluated directly by feasible methods, peripheral investi-
gations are usually made in which a portion of the area is
examined in detail for the reaction to changes in other
parts of the flow phases. Such studies included farm effi-
ciency studies, which indicate the relative proportion of
77
-------
•
• Piezometers
®2" Wells
• Canal Rating Section
0 Drainage Measurement
-Drains
Area Boundary
Stub Ditch
Scale I Mile
Mesa
County
Ditch
rado River
Government
Highline
Canal
Price Ditch
rand Valley Canal
Fig. 17. Location of instrumentation in Area I.
-------
evapotranspiration, deep percolation, and soil moisture stor-
age; land use inventories that yield the respective vegetative
uses being made of the land area and the results of which are
indicative of regional evapotranspiration; and others pertain-
ing to specific areas of water and salt movement. Since
these studies must be conducted on only a portion of the area
under investigation, the assumption was made that they are
representative of the rest of the area.
Instrumentation
The Area I instrumentation illustrated in Fig. 17 provided
valuable data for analyzing the hydrology of the area. The
data collected from these locations were used to delineate
the canal and lateral diversions, drainage outflows, water
table and aquifer pressure fluctuations, and water quality
at the various locations. In order to gain a clearer pic-
ture of the type and limitations of data gathered from each
type of measurement, it is useful to examine them individ-
ually.
Piezometers
The hydrostatic pressures and gradients in the region of
alluvium between the cobble aquifer and the water table were
studied using numerous clusters of 3/8 inch steel pipe pie-
zometers. In each cluster, which contained three to seven
piezometers, the depths were varied so the vertical hydrau-
lic gradient could be evaluated. The small pipe sections
were placed using a jetting technique shown in Fig. 18, and
the same apparatus was also used to periodically flush the
pipes to insure reliable readings. The procedure involved
pumping water under moderate pressure through the pipe which
loosened and carried away the soil below the end of the
pipe, allowing the piezometer to be driven into the soil.
Unfortunately, the method is quite inadequate when rocks or
very heavy clay are encountered. For this reason, the pie-
zometers extended only to the top of the cobble aquifer.
The piezometer installations have several essential uses
in evaluating the subsurface conditions. These include:
(1) The fluctuations in the static pressure were used to
evaluate both the vertical and horizontal hydraulic gradients
in the area. The data from a cluster indicated the vertical
gradients while the scattered clusters containing pipes of
equal depth were used to establish the horizontal gradients.
79
-------
Fig. 18. Project personnel using the jetting technique to
install pipe piezometers.
80
-------
(2) Water quality samples were withdrawn from the pipes,
yielding constituent breakdown, electrical conductivity,
pH, temperature, and quantity of total dissolved solids.
The analysis of these data was used to determine the seas-
onal changes in the quality of the ground water. Some gen-
eralization relating to drainage effectiveness and salt
movements were also determined from these data.
(3) The piezometer locations were used to measure hydraulic
conductivity of the soils employing the pipe-cavity method
outlined by Kirkham (19) . This information was then used
in ground water discharge computations.
(4) Because of the high flows in the open drainage system,
the possibility of certain sections contributing to the
already acute overburden of the ground water system was
studied by installing piezometer lines across selected
drain sections. In this way, the water table level could
be traced and thus establish whether or not the drain was
performing as designed.
(5) Piezometer data throughout the area were examined to
delineate areas of high or low water tables, vertical grad-
ients, undulation in the topography of the cobble, and
perched water tables. This information was also used in
proposing alternate solutions to inefficient drainage.
Two-Inch Piezometers
Owing to the limitation of the piezometer depths, the exam-
ination of the movement of water and salt in the cobble
aquifer was conducted by drilling two-inch diameter holes
encased with steel pipe, with the bottom of the pipe being
located on top of the Mancos Shale, in the middle of the
cobble aquifer, or at the top of the cobble aquifer. The
function of these instrument points has been essentially the
same as that of the smaller piezometers. The larger diameter
facilitates the collection of water samples and determination
of water levels.
The drillers log from each installation defined the topogra-
phy of the subsurface strata to and including the Mancos
Shale. In addition, a few of the pipes were initially con-
tinued a small distance into the shale formation indicating
the presence of small flows within the shale. Because the
number and distribution of these larger piezometers is small,
all pipes were installed in the overlying cobble strata and
the influence of water inside the shale has been assumed
small.
81
-------
Flow Measuring Flumes
The small Parshall and Cutthroat flumes used in this study
were not only used for monitoring drainage discharges as
shown in Fig. 19, but were also used extensively as part of
the special studies on farm efficiency, lateral seepage,
and lateral diversions. At the most important locations
in the area, flumes with continuous stage recorders were
installed to minimize the error in evaluating these dischar-
ges. Since both of these type flumes are primarily designed
for critical depth measurement, attention was given to in-
sure that free flow (critical depth) conditions prevailed
upon installation. Also, the flumes were continually mon-
itored throughout the study to insure free flow conditions.
By operating the flumes in this manner, only the upstream
stage (flow depth) had to be recorded.
A typical installation was constructed by first placing
sandbags in the channel to provide stability in the flume
foundation, which was especially necessary in the open
drains. Experience in doing this work showed other advan-
tages were made possible, such as ease in leveling the
flume, prevention of settling, and more effective sealing
around the headwall of the flumes.
During the course of this study, the problem of maintaining
free flow conditions in the drainage flumes was repeatedly
encountered from channel moss, sediment, and high levels in
the nearby river. In the cases where free flow conditions
were impossible to maintain, the flumes were often raised;
but occasionally this correction could not be made and
considerable accuracy was lost. Fortunately, excellent
efforts by the project personnel minimized these periods.
The flumes ranged in size from six-inch to one-foot Parshall
flumes and one-foot to two-foot Cutthroat flumes. When
properly installed and maintained, these flumes can be
expected to measure a range of flows up to 13 cfs within
about 5 percent accuracy. Those flumes equipped with stage
recorders could also be examined for diurnal flow fluctu-
ations, which provided some insight into the behavior of
the system, but this type of analysis was made only occa-
sionally during the study.
Canal and Lateral Section Ratings
An essential item in the analysis was the determination of
quantities of water diverted from the canals into the lateral
system for irrigation. This was accomplished in two ways:
82
-------
. £.
,
Fig. 19. One-foot Cutthroat flume located in an open drain
in the test area.
83
-------
(1) The smaller capacity canals such as the Stub Ditch,
Price Ditch, and Mesa County Ditches were rated at both the
inlet and exit cross-sections in the test area.
(2) The discharges in the Government Highline Canal and
the Grand Valley Canal were so large (600-650 cfs) that the
effor (e.g., the error would be 2-5 percent for a standard
current meter rating) in the inlet and exit discharge meas-
urements would be greater than the amount of diversions from
the canal in the intensive study area. To remedy this sit-
uation, the turnouts from each canal were individually rated,
Prior to the beginning of the irrigation season, the rela-
tionship between height of thread rod and gate opening for
each of the culvert type turnout gates, illustrated in Fig.
20, located along the lengths of the two large canals were
determined. In addition, datum points were set which were
used in referencing the flow depth upstream of the gate and
the tailwater level at the culvert outlet. Then as irriga-
tion was begun, daily measurements were taken on the gate
opening, elevation of water upstream of the gate, and tail-
water elevations. Since the individual rating of each gate
required considerable time, much of the early data was
collected but not analyzed until some time later. The rat-
ing procedure involved the placement of a Parshall flume
downstream from the gate to measure the flow and then vary
the gate opening over its possible range, noting while doing
this the water level both upstream and downstream.
The rating for a submerged gate with the outlet submerged
is given by:
Q = CdA V2gAh .............. (8)
where Q is the discharge in cfs, C^ is a discharge coeffi-
cient, A is the area of the moon-shaped opening characteris-
tic of circular gates, g is the acceleration of gravity, and
Ah is the difference in elevation between upstream (canal
water level) and downstream (tailwater) water levels. In
the situation where the downstream section is not submerged,
the Ah term would be replaced by hu, the upstream head above
the invert of the culvert inlet. As the problem in the
rating is to establish the value of C^, the values of 0 are
plotted linearly against values of A(2gAh)^ or A(2ghu)^ and
the slope of the resulting best fit line is C^. It should
be noted that a combination of hydraulic conditions can
often cause the plot to be curvilinear. A typical rating
curve is shown in Fig. 21.
The individual section ratings for the inlet and outlet
cross-sections on the small supply canals were derived
84
-------
.Set reference point somewhere on gate
frame to use for measurement to
canal water level.
height of
gate opening"
Invert elev.
Fig. 20. Typical lateral turnout structure used in the
Grand Valley.
Q
cfs
0
ML HO
(12" Parshall)
12" Tube
Fig. 21. Typical discharge relationship for a leteral turnout
rated in the test area.
85
-------
according to common U.S. Geological Survey stream gaging
methods. Current meter measurements were correlated with
daily readings of stage in these canals. One exception to
this effort was the inlet to the Mesa County Ditch, which
has a five-foot adjustable rectangular submerged orifice.
The procedure in this case was the same as indicated above
for the small circular gates. It was assumed that during
the period of this study, the elements affecting such a
rating like moss, bank vegetation, etc., were minimized.
Once this relationship has been established, the daily
stage readings were converted to discharge. Then, the diff-
erence between the inflow and outflow was determined and
corrected for canal seepage loss to arrive at the daily farm
diversion from that section of the canal in the test area.
Peripheral Investigations
Because a number of the segments within the water and salt
system could not be measured with conventinnal instrumen-
tation, it was necessary to conduct special studies of
these items involving primarily the measurement of vari-
ables that are known to influence the parameters in the
modeling process.
Land Use Inventory
The quantity of water transpired from vegetation surfaces
or evaporated from soil and water surfaces can only be meas-
ured using expensive equipment. As an alternative, the
computational methods discussed in an earlier section can
be used conveniently, although some accuracy may be traded.
In order to meet the data requirements of these methods, it
is necessary to determine the type and area of each land
use. This analysis was performed for the entire Grand
Valley (39) with the data subdivided by sections within town-
ships and also by section within townships served by indiv-
idual canals. The procedure involved carrying aerial photos
(1 inch = 1000 feet) into the field and marking the various
land uses according to the index listed in Table 9. Then,
the data were transferred to inked base maps where the
acreage of each land use was evaluated. A summary of these
results has been presented in an earlier section and will
not be further analyzed. Also, a more complete report of
the land use study has been published (39).
While conducting the land use surveys of the valley, the
problem of poor drainage capacities of the soils was visibly
apparent. Although these conditions have persisted for some
86
-------
time, the changes are usually made so slowly that the total
acreage of each classification also varies slowly.
Seepage Investigations
The seepage from conveyance channels in the three project
areas of the study were examined in two parts: (1) lateral
seepage in Area I, and (2) canal seepage in Areas I and III.
This type of study was conducted before and after the lin-
ings had been constructed along the lengths of the Stub
Ditch, Price Ditch, Government Highline Canal, and Mesa
County Ditch. In addition, before and after measurements
were made along the Redlands First Lift Canal.
The ponding method for determining seepage loss rates was
selected to assure accurate measurements, especially in the
large canals,since the degree of error inherent in using
inflow and outflow measurements procedures would tend to
mask the magnitude of seepage losses. The ponding method,
illustrated in Fig. 22, consists of placing an impervious
barrier at two or more locations along the canal, filling
each isolated section with water, and then taking periodic
measurements on falling water elevations that can then be
used to evaluate the seepage rate. The length of individ-
ual canals was diked into a number of ponds depending on
the grade and length of the canal, with headgates extend-
ing through each dike in order to regulate water levels in
subsequent ponds. The rate at which the water surface
dropped in each pond was measured with either a staffer
hook gage. Finally, a survey of the canal cross-sections
provided the geometric data necessary for the rate compu-
tation expressed as:
AE • SW • 24
Q = a (9)
r WP -T
a r
where Q is the loss rate in ft3/ft.2/day (abbreviated as
cfd), A£ is the drop in water surface elevation in feet
during the length of run, Tr is the time of the run in
hours, SWa is the average water surface width in feet tes-
ted during the run, WPa is the average wetted perimeter in
feet during the run, and 24 is the number of hours per day.
The lateral seepage study was conducted in a different manner
because of the high grades and small flows. It should be
noted again that the term "lateral" refers to the small con-
veyance channels that carry water between the canals and
the fields. The Area I lateral system shown in Figs. 23,
24, and 25 was investigated using inflow-outflow discharge
87
-------
Fig. 22. Canal seepage measurement using the ponding method,
88
-------
•
Fig. 23. Lateral system supplied by the Stub Ditch, Price Ditch, and Government
Highline Canal in Area I.
-------
-------
Fig. 25. Lateral system supplied by the Mesa County Ditch in Area I
-------
measurements. During most of the study, small Parshall flume
flumes were used, but several unusual conditions were encoun-
tered where current meters and bucket-stop watch measurements
were used. Flumes were located at the inlet and exit sections
and at all inflows and diversions. The main channel sections
usually required either a six- or nine-inch Parshall flume,
while the inflows and diversions usually could be measured
with two- and three-inch Parshall flumes. As the work pro-
gressed, two conclusions became apparent: (1) the seepage
rate was small in comparison to the flows so a length of at
least two thousand feet was necessary before the results
would be relaible; and (2) the number of inflows and diver-
sions must be somewhat restricted or the inaccuracy in the
flumes, no matter how well operated, would be as large as
the seepage loss in the section. Because of these limita-
tions, not every lateral in Area I was suitable for measur-
ing seepage loss rates. The procedure for an individual
length of lateral could be satisfactorily completed during
a day.
Farm Efficiency Studies
The efficient use of water on the farm would be achieved
when the total quantity of water entering the field was
sufficient enough to meet the demands of the crops, soil
surface evaporation, and the quantity of water necessary to
leach the residual salts of the evapotranspiration process
from the root zone. Factors that decrease farm water use
efficiency in Grand Valley are numerous and result in exces-
sive deep percolation losses and high field tailwater flows.
Irrigation efficiency is a good, although indirect, exam-
ination of the areal magnitudes of deep percolation, drain-
age interception, consumptive use, and field tailwater.
As noted earlier, without expensive and complex instruments
farm efficiency studies become the most feasible method of
estimating these variables.
The principal parameters related to evaluating on-farm water
use include:
(1) Field tailwater which was measured with small Parshall
or Cutthroat flumes.
(2) Deep percolation and leaching requirements derived from
budgeting the root zone flows.
(3) Root zone storage changes measured by soil moisture
sampling and correlated neutron probe techniques.
92
-------
(4) Evapotranspiration which was computed using methods
that were discussed earlier.
(5) Uniformity of applications evaluated from soil mois-
ture samples, as well as advance and recession analysis.
(6) Precipitation.
Since the initial phase of the project did not include soil
moisture measurements, the results are primarily useful for
analyzing irrigation methods and the extent of the surface
flows. During the post-construction study phase, two farms
(Fig. 26) were selected for study. In addition to the usual
water budgeting analysis that was performed, advance-reces-
sion experiments were conducted in order to evaluate the
effects of various irrigation practices on efficiency. Also,
the analyses of soil samples for salt contents was added to
this study so that the effect of irrigation on salt movement
could be evaluated.
Subsurface Explorations
In addition to soil sampling efforts that gave considerable
insight into the soil conditions, and piezometers and wells
that indicated qualitative conditions below the root zone,
an investigation was made throughout the test area to sample
and evaluate salts and moisture content to a depth of about
twenty feet. Examination of these data (summarized in Fig.
27) indicated the changes that are evident in the vertical
section, and also showed the conditions throughout the
region. One of the interesting generalizations that could
be made from evaluating soil moisture and soil salt content
throughout an area was the effects of poor drainage. For
example, in the region in which the water tables were high,
the process of capillary action and consequent evaporation
from the soil surface would concentrate salts in the upper
levels of the profile. The lower levels of soil profiles
occurring in high water table areas were expected to have
a more representative salt concentration of the area since
the water at these levels was slowly being drained. The
exact opposite should be expected in well drained soils as
the leaching action would remove salts in the root zone and
concentrate them in the lower soil levels.
Drainage Evaluations^
During the early stages of this project, the effectiveness
of the open drainage system was questioned. As a result,
93
-------
Stub Ditch
Government
Highline —
Canal
Scale I Mile
Fig. 26. Location of farm efficiency studies conducted in Area I
-------
0
v
8
V
G
1C
D Road
E Road
F Road
Water Table
Elevation
0 5 10 15 20
Specific Conductance x I03 mmhos/cm
25
Fig. 27. Summary of Area I soil sampling data
95
-------
special piezometer installations were installed across cer-
tain drain sections to examine the piezometric surface as
influenced by the drains. To complement the piezometer data,
small Parshall and Cutthroat flumes were installed throughout
the open drainage system in the test area to monitor dischar-
ges. These data indicated the magnitudes of losses or gains
occurring in the reaches.
The magnitude of the salinity problem, along with the ineff-
ectiveness of the drainage system in Grand Valley, required
investigative attention in order to clearly delineate the
effectiveness of improved drainage as a salinity control
measure. While the data collection for this project was
neither conducted for that purpose, nor indicated conclusive
solutions, it does provide some basis regarding the influence
of conveyance channel seepage upon the drainage problem.
96
-------
SECTION VIII
WATER QUALITY CHARACTERISTICS
OP THE GRAND VALLEY
With increasing water development in the Upper Colorado
River Basin, effective salinity control measures are nec-
essary to prevent extensive economic loss to lower basin
users. Because the greatest impact of salinity is in
the lower reaches of the river system (while most of the
salt loads originate in the upper basin), the problem must
be examined regionally. It is apparent that the alterna-
tives available to the upper basin states relate almost
exclusively to reducing salt inflows in order to offset
transbasin diversions, as well as making reductions for
the developments in the basin. Future increases in salt
concentrations at Lee's Ferry, Arizona have to be mini-
mized, or halted.
The feasibility of most of the presently conceived salinity
control measures will be established in the near future.
This project has examined, for purposes of reducing seepage
losses, the possibility of lining conveyance channels.
These seepage losses eventually transport large salt loads
from the subsurface areas into the river system. However,
most situations being encountered suggest that other manage-
ment alternatives are not completely independent of canal
and lateral lining or rehabilitation of distribution sys-
tems in general. For this reason, an attempt has been made
in the following sections of the report to examine the
results of this study in a broader perspective of salinity
control measures, rather than just canal lining.
Neither the scope of this project nor the period of study
justifies an extensive water quality data analysis. Never-
theless, a certain amount of discussion of the water quality
characteristics of the area provides useful insight to the
nature and problems of Grand Valley. Water quality data from
the USGS stream monitoring stations in the Grand Valley area
have been combined with a great deal of data collected as
part of this study in order to reflect the chemical quality
of the various segments of the hydrologic system in the
valley.
The water quality parameters most representative of salinity
include temperature, specific conductance, total dissolved
solids, pH, calcium, magnesium, sodium, potassium, carbonate,
bicarbonate, chloride, sulfate, and nitrate. This basic
97
-------
information can also be used to evaluate other indicator
variables such as the relative activity of sodium. Water
quality in an agricultural area varies with both discharge
and the season. Thus, the water quality data have been
grouped together according to the various hydrologic com-
ponents of the water system and discussed in a general
nature. The analysis of the Grand Valley water quality char-
acteristics has been divided into the following groups:
(1) River inflows and outflows
(2) Drainage return flows
(3) Water table
(4) Aquifer flows
Surface Strearoflow
The principal points of study relative to the valley inlet
and exit sections are the U.S. Geological Survey stations
from which all existing data were collected. These include:
(1) Colorado River, near Cameo, Colorado
(2) Plateau Creek, near Cameo, Colorado
(3) Gunnison River, near Grand Junction, Colorado
(4) Colorado River, at the Colorado-Utah State Line
Data relating complete constituent breakdown were extracted
from USGS reports and summarized. In Fig. 28, the mean annual
flow and its corresponding salt load in total dissolved solids
expressed as tons are shown. The period of record was the
1969 water year. Several assumptions were made in arriving
at this pictorial flow diagram. First, since no data were
available, it was assumed that the water quality of Plateau
Creek was the same as the Colorado River. Secondly, the
estimates of precipitation and consumptive use were made
from information reported by other researchers (7,14,16).
Fig. 28 indicates that through Grand Valley there is a net
consumptive use of 299,200 acre-feet and an input of one
million tons of salt annually. About 55 percent of the con-
sumptive use is from irrigated croplands. Taking into
account all of the lands in Grand Valley, which includes
lands with phreatophytes, the water use amounts to about
2.5 acre-feet per acre per year, while the salt contribution
is 8 tons per acre annually. It should be strongly empha-
sized that these figures represent a period of one year and
may not be representative of the general condition.
The information shown in Fig. 28 does indicate the magnitude
of the flow system in Grand Valley, but further examination
is needed to establish the specific effects. For example,
Fig. 29 shows the mean annual flow diagram through the valley
98
-------
Plateau Creek near
Cameo, Colorado
(169,200 acre-ft.)
Discharge
Precipitation
(75,000 acre-ft.)
Gunnison River near
.Grand Junction, Colo.
(2,253,000 acre-ftj
Colo. River near
Colo-Utah line
^5,488,000 ac-ft)
Colorado River near
Carneo, Colo
(3,290,000 acre-ft.)
Evapotransportat ion
(299,200 acre-ft.)
Salt
Plateau Creek near
Cameo, Colo
(200,000 Tons)
Tributary inflow
resulting from
precipitation
(100,000 Tons)
Gunnison River
Grand Junction, Co.
(1,800,000 Tons
Colorado River
near Cameo, Colo.
(2.600,000 Tons)
Grand Valley contribution
(900,000 Tons)
Colorado River
near Colo-Utah
line
(5,600,000 Tons)
Fig. 28. Illustrative diagram of the water and salt flows in the Grand Valley area
during the 1970 water year.
-------
275
SAP
Gunnison River
near Grand Junction
Colo.
Colorado River
near Colo-Utah
state line
1.24
Plateau Creek
near Cameo, Colo
Colorado River near
Cameo, Colo
SSP
Plateau Creek
near Cameo, Colo
43.8
River near
Grand Junction, Colo.
345
Colo. River near
Colo.-Ulah state
line
Colorado River near
Cameo, Colo.
438
Fig. 29. Diagram of sodium adsorption ratios (SAR) and soluble
sodium percentage (SSP) in the Grand Valley during
the 1970 water year.
100
-------
in terms of the sodium adsorption ratio, SAR, expressed as
SAR =
in which the brackets refer to the ionic concentration in
millieguivalents per liter. Also, Fig. 29 shows the solu-
ble sodium percentage, SSP, through Grand Valley. This
parameter (SSP) is expressed as
+
[(Na
Of specific interest to irrigators is the indication that the
harmful dispersing attributes of sodium ions are reduced by
the return flows from Grand Valley. In addition, the red-
uced SAR value at the mouth of the Gunnison River would also
seem to indicate that upstream irrigation reduces the sodium
effects, since the irrigated acreage in the Gunnison River
Basin is much larger than that of the Colorado River Basin
above Grand Valley. In order to delineate the magnitude of
the ions in terms of annual flows, the cation breakdown has
been summarized and presented (Fig. 30) . Since no effort
was made to evaluate the changes that occur in these vari-
ables with time, a frequency distribution diagram of SAR
for the three principal gaging stations has been included
in Fig. 31.
Further analysis of the USGS water quality data in the river
system can be made by examining the relationship between
total dissolved solids and specific conductance. Because
of the limited nature of the data and the scatter encountered,
the regression between the two variables was made linear.
The results are tabulated below.
Table 16. Linear regression analysis of specific conduct-
ance in ymhos/cm and total dissolved solids in ppm
for Colorado and Gunnison River stations. (EC =
m-TDS + B) .
Name of
Station
Colo River
near Cameo
Gunn River
near
G. Junction
Colo River
at
Colo-Utah
State Line
Slope, m
1.247
1.132
1.372
Inter-
cept, B
177
119
176
Correlation
Coefficient, R
0.970
0.998
0.970
Number
of Samples
29
43
12
101
-------
Plateau Creek
(2991 Tons)
Colorado River
near Cameo, Cd" '•'*
(58,167 Tons)
Plateau Creek
near Cameo, Colo
(11,966 Tons)
Colorado River
near Cameo,Colo
(232,669 Tons)
Plateau Creek
(6,413 Tons)
Colorado River
near Cameo, Cod
(299,735 Tons)
Plateau Creek
(667 Tons)
Gunnison River \\
near Grand June. >^j
(72,005 Tons)
Colorado River
near Goto.-Utah Line
(237,345 Tons)
Grand Valley
(104,182 Tons)
r-_-n
Ca
Gunnison River'
near Grand June.
(205,293 Tons)
Colorado River
near Colo-Utah Line
(634,413 Tons)
Grand Valley
(184,485 Tons)
Na*
Gunnison River
near Grand June.
(119,499 Tons)
Colorado River
near Cameo, Colo
(12,976 Tons)
Grand Valley
(192,247 Tons)
Gunnison River
near Grand June
(9,039 Tons)
Colorado River
near Colo-Utah Line
(626,747 Tons)
Colorado River
near Colo-Utah
(26,869 Tons)
Line
Grand Valley
(4,187 Tons)
Fig. 30. Diagrammatic presentation of cation flows through
the Grand Valley during the 1970 water year.
102
-------
4.0
tr 3.0
<
C/3
10
Colorado River Near
Cameo, Colorado (1970)
0
25 r
20
o:
<
Cfl
:
0.5
10 20 30 40 50 60 70 80 90 100
Percentage of Time SAR is Less Than or
Equal to That Shown
Gunnison River Near Grand
Junction, Colorado (1970)
10 20 30 40 50 60 70 80 90 IOO
Percentage of Time SAR is Less Than
or Equal to That Shown
3.0
25
a20
:
Colorado River at Colorado-Utah
State Line (1970)
'•°' l& £0 30 40 50 60 70 80 90
100
Percentage of Time SAR is Less Than
or Equal to That Shown
Fig. 31. SAR frequency at three USGS stream gaging station in
the Grand Valley during 1970 water year.
103
-------
The frequency of specific conductance at these stations,
along with a bar graph summary of constituents, has been
included in Figs. 32, 33 and 34. The ratio of TDS to EC for
the Colorado River stations would vary between 0.62 and 0.70
for the usual salinity concentrations encountered in this
river.
Drainage Return Flows
From data collected and analyzed as part of this effort, an
analysis similar to that in the preceding section can be
made. Samples from each drain in the intensive study area
have been combined with a large number of periodic samples
from drains and washes throughout the valley. The average
constituent composition and frequency of specific conduct-
ance are shown in Fig. 35, along with the frequency of SAR.
A point concerning the imbalance between anions and cations
shown in the bar graph of Fig. 35 is made. During the
analysis of the project data, all parameters were measured
and recorded directly. As a result, some error exists in
the laboratory analysis. Also, some constituents such as
phosphate and iron were not measured, which can lead to an
imbalance between cations and anions. In order to compare
the average chemical quality shown in the bar graph of
Fig. 35 with data specifically collected in the study area,
Table 17 has been included to illustrate the variation in
chemical quality between the open drains and natural washes.
Several considerations of these results should be noted. It
has been assumed that the entire surface drainage system is
similar, which is not completely correct. As pointed out
earlier, many natural washes and drains are used to convey
canal spillage back to the rivers, and every drain carries
high percentages of field tailwater. Accordingly, there is
a large dilution effect that occurs at various points within
the system. The linear regression between specific conduct-
ance and total dissolved solids for the chemical quality data
representative of the drains and washes indicates the follow-
ing relationship:
EC = 333 -I- 0.851 • TDS (12)
with a correlation coefficient, R, of 0.981. When this partic-
ular regression was performed logarithmically, the R value
was only 0.94.
104
-------
Co
•
n
200,
"0 10 20 30 40 50 60 70 80 90 100
Percentage of Time Specific Conductance
is Less Than or Equal to That Shown
Fig. 32. Bar graph of constituent analysis and frequency diagram for specific conduc
tance of water samples of the Colorado River near Cameo, Colorado during 1971
water year.
-------
'
n
I I I I I I 1 1
'0 10 20 30 40 50 60 70 80 90 100
Percentage of Time Specific Conductance
is Less Than or Equal to That Shown
Fig. 33. Bar graph of constituent analysis and frequency diagram for specific conduc-
tance of water samples of the Gunnison River near Grand Junction, Colorado
during the 1970 water year.
-------
NaUIU
Mg"1
Ca+1
Iso;
la
\
0
300
'0 10 20 30 40 50 60 70 80 90 100
Percentage of Time Specific Conductance is Less
Than or Equal to That Shown
Fig. 34. Bar graph of salt constituents and frequency of specific conductance of samples
from the Colorado River at Colorado-Utah State Line during 1970 water year.
-------
Composite of Valley Drains
And Washes (1968-1971)
Na+{ZD
10 20 30 40 50 60 70 80 90 100
Percentage of Time Specific Conductance
is Less Than or Equal to That Shown
Fig. 35
9r
8 -
7
I I
I I
I I
10 20 30 40 50 60 70 80 90 100
Percentage of Time SAR is Less Than or
Equal to That Shown
Bar graph of constituents and frequency diagram of
specific conductance of water samples for drains and
washes in the Grand Valley.
108
-------
Table 17. Average constituent breakdown in epm for drains and washes.
Flume 1
Flume 2
Flume 3
Flume 4
Flume 5
Flume 6
Flume 7
Flume 8
Flume 9
Little Salt Wash
at HWY 6 & 50
Indian Wash at
C-5 Rd.
West Salt Wash at
HWY 6 & 50
Hunter Wash at
River Road
Big Salt Wash at
HWY 6 & 50
Mack Wash 1 mi west
of Mack, Colo
Badger Wash at
HWY 6 & 50
East Salt Wash at
HWY 6 & 50
Composite Average
of Drains & Washes
Captions
c."
15.37
9.53
9.66
14.49
9.20
14.64
12.72
9.85
12.32
5.86
12.68
10.70
10.70
11.33
12.07
13.10
13.46
11.56
"o"
23.28
10.00
16.05
30.95
15.47
26.28
26.81
14.74
10.37
8.98
18.33
11.31
8.77
6.53
9.69
12.66
12.34
13.93
Na
17.24
11.18
12.86
21,40
13.50
19.89
19.96
14.14
9.97
10.29
16.29
12.77
12.27
9.93
6.93
12.28
12.24
12.61
K+
0.22
0.17
0.23
0.29
0.20
0.30
0.25
0.22
0.21
0.14
0.35
0.17
0.20
0.17
0.15
0.19
0.22
0.21
Anions
HCO~
6.00
5.02
5.12
6.91
5.12
6.47
5.64
4.63
3.42
3.64
4.31
3.77
3.81
4.68
3.08
4.30
4.35
4.50
C°3
0.10
0.08
0.04
0.12
0.12
0.14
0.17
0.24
0.25
0.13
0.13
0.12
0.05
0.13
0.16
0.19
0.18
0.15
(
8
5
5
7
5
6
6
4
4
3
5
3
3
3
2
3
4
4
:i~
.21
.65
.53
.42
.25
.89
.20
.80
.68
.42
.49
.48
.73
.34
.82
.14
.51
.88
S°I
28.52
22.40
28.35
40.27
21.15
47.45
41.58
29.51
25.72
12.49
32.09
17.07
20.32
17.34
10.49
22.62
19.95
25.00
NO3
0.46
0.06
0.13
0.33
0.16
0.70
0.43
0.71
0.05
0.15
0.79
0.11
0.19
0.15
0.13
0.24
0.21
0.28
SAR
3.92
3.58
3.59
4.49
3.84
4.40
4.49
4.03
2.96
3.78
4.14
3.85
3.93
3.32
2.10
3.42
3.41
3.53
-------
Near-Surface Ground Water
The collection of samples from piezometers located in the
intensive study area was difficult at best. Often the sample
was too small for analysis, and at other times no sample
could be obtained. For this reason, a large number of samples
of water below the water table were made, but the number for
each individual peizometer was small. The frequency of SAR
along with the constituent analysis and frequency of specific
conductance are illustrated in Figs. 36 and 37 respectively.
An attempt was made to evaluate the relationship between EC
and TDS with the result
EC = 0.913 • TDS + 100.0 (13)
in which R = 0.97. Although the coefficient of 0.913 is very
high in comparison with the usually quoted ratio of 0.64
(TDS/EC), this result is corroborated by water quality analy-
ses performed by the USER on samples collected from drains
and washes in Grand Valley.
Deep Ground Water
The water quality data collected from the two-inch wells in
the cobble aquifer are summarized by frequency of SAR and EC,
along with a bar graph indicating chemical composition in
Figs. 38 and 39 respectively. The regression analysis indi-
cated the following relationship:
EC = 1.00 • TDS + 0.5 (14)
with a correlation coefficient, R, of 0.94. Again, the
ratio of TDS to EC is very high, being 1.00. The EC and TDS
values consistently have nearly the same value for the drain-
age waters, where salinity concentrations of 5,000 - 10,000
ppm are encountered, with occasional samples having EC and
TDS values of 15,000 (mg/1 or micromhos/cm).
Summary and Conclusions
Although a severe degradation in water quality (as measured
by increased TDS levels) occurs in Grand Valley, an examin-
ation of several indicator parameters, such as the sodium
adsorption ratio, show that the activity of sodium is being
reduced. Since much of the salt contribution from the
Mancos Shale is primarily Ca, Mg, and SO4, a reduction in
SAR would be expected.
110
-------
Composite of Piezometer Somples
No
Mg
Cd
IS04=
Icr
iHCOi
I 100 r
10 20 30 40 50 60 70 80 90 100
Percentage of Time Specific Conductance
is Less Than or Equal to That Shown
Fig. 36. Bar graph of constituents and frequency diagram of
specific conductance of water samples from the near-
surface groundwater in the test area.
10 20 30 40 50 60 70 80 90 100
Percentage of Time SAR is Less Than or
Equal to That Shown
Fig. 37. Frequency diagram of SAR from water samples of near-
surface groundwater.
Ill
-------
Composite of Aquifer Samples
Nalll]
to
120
100
80
60
v
I 20
cr
10000r
g 9000
c
8OOO
o
70OO
o o
y -i 60OO
o
g.
en
^5000
4000
3000
I 1
I I
10 20 30 40 50 60 70 80 90 100
Percentage of Time Specific Conductance
is Less Than or Equal to That Shown
Fig. 38. Bar graph of salt constituents and frequency of
specific conductance of aquifer samples in the
test area during study period.
Fig. 39
I
3
< 9
2 7
-:
10 20 30 40 50 60 70 80 90 100
Percentage of Time SAR is Less Than or
Equal to That Shown
Frequency of SAR of aquifer samples.
112
-------
The total contribution of total dissolved solids to the river
network approaches 1 million tons annually during periods of
plentiful water. During years of low flow, as indicated by
lorns, et. al. (16), this contribution is only approximately
half the peak inputs.
The quality samples from the ground water of both the near-
surface and cobble aquifers show that sulfates of calcium,
magnesium, and sodium represent the bulk of salinity from
the Grand Valley, although some significant quantities of
chloride salts also are present.
The linear relationships between TDS and EC indicate that
the ratio is near 1:1 for the drainage waters. For the
surface waters in the Colorado River, the ratio of TDS to
EC is between 0.62 and 0.70, which is the ratio usually
quoted in the literature.
113
-------
SECTION IX
EVALUATIONS OF THE CONVEYANCE SYSTEM
Consideration of the water distribution system is an essen-
tial part of most salinity control alternatives, which sug-
gests that a broader perspective of system improvement as
a salinity control alternative is required. The delivery
system in the valley is divided into the canal or ditch sub-
system and the lateral subsystem. The divisionbetween the
two subsystems is based on management responsibility. The
canal companies and irrigation districts divert the approp-
riated water right from the river, transport the water in
the canal subsvstem, and control the delivery of water
through the canal turnout, but they generally assume little
responsibility for the water below this point. The canal
and ditch subsystem can thus be defined as that part of
the delivery network which is controlled by irrigation
authorities. The lateral network, extending beyond the
turnout from the canal or ditches, is managed by cooperative
agreements between the individual users served by the turn-
out. The transfer of responsibility between the two phases
should be the equitable measurement and charge for the
water at the turnout, but there is little incentive to make
this effort with the abundance of water, A notable excep-
tion are the turnouts comprising the Water Users Association
under the Government Highline Canal, where individual meas-
urements are made and recorded.
Canal System
The canals and ditches in the Grand Valley, shown in Fig. 40,
are operated and maintained by the respective organizations
mentioned earlier. Discharge capacities at the head of the
canals range from above 700 cfs in the Government Highline
Canal to 30 cfs in the Stub Ditch and diminish along the
length of each canal or ditch. The lengths of the respect-
ive canal systems are approximately 55 miles for the Govern-
ment Highline Canal, 12 miles each for the Price, Stub, and
Redlands Ditches, 110 miles for the Grand Valley system, and
36 miles for the Orchard Mesa Canals. Individual aspects of
the canal system are discussed below.
Operation
The management of the canals and ditches in the area varies
between canals, as well as with changes in the water supply.
115
-------
H-
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h
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fi
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tn
' :
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Tovnthip Indtx for Th« t3rand ValUy
-------
For example, it was noted earlier that during periods when
river flows become small, restrictions are placed on the
diversion into the Government Highline Canal. This is
possible because the flows are measured and recorded at
each individual turnout in that system, and it is required
since their water rights are junior to others. On the
other hand, in most instances along the other canals meas-
urements are not made because little shortage is experi-
enced. Another practice used extensively in the region is
the regulation of canal discharges at points in the system
by varying the amounts of spillage into the natural waste-
ways and washes. Neither of these practices - inadequate
flow measurement and canal spillage - is conducive to
salinity control.
The dilemmas being faced by irrigation officials are numer-
ous, but can be traced to one factor. When the demand for
irrigation was realized and the canal alignments located,
the expected demand for water was based on the total area
of land under the canal. However, when the acreages of
roads, homes, phreatophytes, etc., are deducted, the water
available for each acre is significantly increased. For
example, under the Grand Valley Canal are 44,774 acres of
which only 28,407 are irrigable. Consequently, instead of
having a water duty (annual volume of water diverted from
the river per unit area) of 5.76 acre-feet per acre, there
is more than 9 acre-feet per irrigable acre. The result
is a two-fold problem:
(1) With the excess of water available to the irrigators,
it is more economical to be wasteful because failure to
provide adequate water to crops during critical growing
periods can affect yields more than an over-irrigation.
(2) The history of development in the western United States
has always shown water to be a valuable commodity to an area
and as such, the rights one has are to be protected since
the rights not historically diverted are lost. Consequently,
the Grand Valley must divert its rights for fear of losing
them.
In short, it is not the practice of agriculture to be waste-
ful, but the laws regulating the use of water dictate that a
user either be wasteful or give up a valuable right.
Canal Seepage
The initial phase of this study involved the determination
of the seepage rates from the canals and laterals in the test
areas (Area I, II and III). The ponding technique was
117
-------
employed to assure reliability of the results. The first
tests were conducted on all canals in Area I except the
Grand Valley Canal. The lengths evaluated included a 2.6
mile section of Stub Ditch, 2 miles of Government Highline
Canal, 1.9 miles of Price Ditch, and 2.2 miles of Mesa
County Ditch. In addition, the tests were made along the
0.5 mile length of the Redlands First Lift Canal in Area III.
The 0.15 mile length of Grand Valley Canal in Area II was
not evaluated because of the high seepage losses being evi-
dent. Also, the construction costs for dikes and tests in
relation to the costs of the lining in Area II would have
resulted in the testing being more expensive than the lining.
A summary of the test results is shown in Table 18, indicat-
ing only moderate seepage rates in Area I and a relatively
high rate in the Redlands First Lift Canal. The average
seepage rates were approximately 0.15 ft3/ft2/day (cfd) in
the Stub, Price, and Mesa County ditches; 0.25 cfd in the
Government Highline Canal; and an average rate of 0.40 cfd
in the Redlands First Lift Canal.
Although canal size and depth to the water table may be sig-
nificant factors influencing seepage rates, the results
seem to contradict those of previous investigations. The
water table depths in the area of the Stub Ditch, Government
Highline Canal and Price Ditch are similar, but the large
canal has a noticeably large seepage rate yet it is much
more affected by the shale. Nonetheless, it seems justified
to conclude that seepage rates in the Grand Valley canals
probably vary between 0.15 and 0.40 cfd. Extending these
results to the entire valley, the estimated conveyance
losses attributable to seepage probably range between 25,000
and 65,000 acre-feet annually, which would mean that between
4% and 10% of the annual diversion results in seepage from
canals into the ground water system.
Because the influence of the water table would serve to
reduce canal seepage, the location of linings in the low-
lying areas may not be as effective as in the upper eleva-
tions in the valley to the north. In the principal study
area, the water table in many places is higher than the
bottom of the Grand Valley Canal and the seepage rates would
be reduced.
Linings
Based upon the results of the ponding rests, two modifica-
tions to the original proposal (Table 19) were recommended
and incorporated in the project. The first recommendation
was that the lining of the Government Highline Canal in
Area I should be constructed on the downhill bank of the
118
-------
Table 18. Results of ponding tests on canals in Area I
and II .
Canal Pond
no .
Mesa County 1
Ditch 2
3
4
5
6
7
8
9
Government
Highline Canal 1
Price Ditch 1
2
3
4
5
_
Stub Ditch 1
2
3
4
5
6
— —
Redlands First 1
Lift Canal 2
. — —
Avg. Wetted
Length Midstation Perimeter
(ft) (^)
1300
1075
1367
1227
1025
1316
1250
1449
1184
4925
R?78
1930
1960
2000
2035
1865
_,
2175
2150
2600
2300
2275
2375
1213
1318
6 + 50
18 + 37
30+57
43+55
54 + 82
66+52
77 + 85
92+85
106+02
28+37
79 + 39
10+67
30 + 60
50+00
70 + 17
89 + 67
—
11+62
33+25
52 + 06
81+50
104+37
127+62
_ •
6 + 06
19 + 02
11.81
12.12
12.14
11.20
10.40
12.22
12.42
12.34
12.59
54.92
59.18
15.91
16.41
10.01
12.22
14.12
10.53
12.34
10.84
13.50
11.69
10.68
15.30
14.38
Seepage Q*
Rate Acre-ft
(cfd) Season
0.12
0.13
0.12
0.15
0.15
0.17
0.18
0.13
0.13
Total
0.25
0.25
Total
0.12
0.13
0.11
0.11
0.16
Total
= ; — i ==
0.15
0.13
0.15
0.12
0.13
0.22
Total
0.45
0.35
Total
8. 46
7.78
9.12
9. 40
7.13
12.40
12.80
10.62
8.59
86
310.70
358.30
669
16.67
19.00
19.20
12.40
19.20
86
=====
15.60
15.60
19.40
17.10
15.80
25.60
109
38.20
31.80
70
*Based on 200-day season
119
-------
last mile in the study area. The objective of changing from
a complete perimeter lining as originally proposed was to
make an evaluation of the effectiveness of the downhill lin-
ing in reaches where the canal is located in the shale for-
mations. The second change involved reducing the construc-
tion scheduled for the drainage system to two small surface
problems in the area and the remainder of these funds be
spent on lateral linings. The field data indicated that
most drains were performing as intended and not seeping
water back into the ground water. The linings which were
constructed in the canal system as a part of this project
are illustrated by the darkened lengths in Fig. 41. The
cost estimates of the original proposal listed in Table 19
can be compared to the final estimated costs tabulated in
Table 20.
The Stub Ditch linings consisted of the standard trapezoidal
slip form concrete lining, as shown in Fig. 42. The loca-
tion of the Stub Ditch, which runs to just east of Grand
Junction, is along the extreme northern edge of the irrigated
area of the valley, characterized by rapid and numerous undul-
ations in the topography, causing the canal alignment to
assume a very winding path. As a result, the Stub Ditch is
often in close proximity to the Government Highline Canal, as
indicated in Fig. 42. The linings in the Price Ditch system
in Area I and the Redlands First Lift Canal in Area III were
of the same nature (trapezoidal slip form) as the Stub Ditch
linings. ,;
The other commonly used type of lining in the area was the
gunnite material used for the Mesa County Ditch, as shown
in Fig. 43. It is of some interest to note the white cov-
ered field in the background in Fig. 43, a good illustration
of the surface accumulations of salts resulting from poor
drainage. This type of lining has several advantages to
the local irrigation companies since they are already equipped
to accomplish the work and the limited preparation for the
linings does not tie up too many people. This same procedure
was also used along the short section of the Grand Valley
Canal in Area II and the downhill bank lining of the Govern-
ment Highline Canal in Area I.
The construction of the small drainage improvements in the
project is illustrated in Fig. 44. The figure indicates the
utility of such a design for a farming area since it reduces
the land area occupied by the open drainage system.
An often overlooked aspect of a lining program is the addi-
tion of appurtenances to the canal and the rehabilitation
of the system in general. Two examples are shown in Fig. 45,
120
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Stub Ditch
• i
Government
Highline
Canal
Price Ditch
Scale I Mile
Grand Valley Canal
Mesa County
Ditch
Colorado River
Fig. 41. Location within Area I of the linings that were
constructed,
-------
Table 19. Proposed canal lining construction cost.
Map
Design-
ation
Company Name
Canal Name
Pori- Unit Total
Type Length meter Area Cost Cost
(mi.) (ft.) (ydz) ($7ydT) ($)
Area I
A
D
Area II
Area III
Grand Valley Irrigation Co,
Mesa County Canal
Palisades Irrigation Dist.
Price Ditch
Grand Valley Water Users
Assn. Highline Canal
Mesa County Irrigation Co.
Stub Ditch
Grand Junction Drainage Co.
Open Drains
Other Drains
Grand Valley Irrigation Co.
Grand Valley Canal
Redlands Water & Power
Gunnite 2.5 15 22,000 3.25 71,500
Gunnite
Slip Form 2
15 17,600 3.25 57,200
Gunnite 1.5 30 26,400 3.25 85,700
10 11,800 3.25 38,200
Slip Form 6 5 17,600
1.2 10 7,100
3.25 57,400
3.25 23,000
Gunnite .15 22 2,900 3.25 9,500
Slip Form .5 12 3,500 3.25 11,500
TOTAL
354,000
-------
Table 20. Recommended construction program.
Map
Design-
ation
Area I
A
B
C
D
Area II
F
Area III
G
Company Name
Canal Name
Grand Valley Irrigation Co.
Mesa County Canal
Palisades Irrigation Dist.
Price Ditch
Grand Valley Waters Users
Assn. Govt Highline Canal
Mesa County Irrigation Co.
Stub Ditch
Grand Junction Drainage Co.
Open Drains
Closed DRains
Laterals
Grand Valley Irrigation Co.
Grand Valley Canal
Redlands Water and Power
First Lift Canal
Type of
Lining Length
(mi)
Gunnite 2.2
Slip Form 1.9
Gunnite 1,0
Slip Form 2.5
Slip Form
Tile
Slip Form
Gunnite 0.15
Slip Form 0.5
Peri- Unit
meter Area Cost
(ft.) TycP") ($7yd^)
14 17,500 3.25
15 16,720 3.25
15+ 8,800 3.50
10 14,700 3.25
15+ 1,320 3.50
12 3,500 3.25
Misc. Total
Costs* Cost
($) ($)
2,100 58,975
1,900 56,240
5,800 36,600
3,500 51,275
4,000
16,000
110,815
4,000 8,620
1,600 11,475
TOTAL
*Costs of pre-construction and post-construction ponding tests above amounts
in CSU contract, plus costs of installing headgates, etc.
+Downhill bank lining, only.
354,000
-------
Fig. 42. Slip form concrete lined section of the Stub Ditch,
124
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Fig. 43. Gunnite lined section of the Mesa County Ditch.
125
-------
Fig. 44. Tile drain line in the study area.
126
-------
:
Fig. 45. Special purpose structures built as part of the
lining work.
127
-------
showing first in the lower picture a box-type culvert
arrangement to convey surface runoff from adjacent lands
over the Stub Ditch to avoid destruction of the lining.
The second (upper) picture shows a typical circular slide
gate turnout along the Price Ditch. These additions to
the canal allow and promote better management of diversions
being made into the lateral system.
Results of the Lining
An adequate evaluation of the operation and maintenance ben-
efits attained from the linings was difficult. Correspondence
with officials of the Grand Valley Water Purification Project,
Inc., most of whom are also serving as local irrigation and
drainage officials, has delineated certain benefits resulting
from the lining program.
The initial step upon completion of the construction was to
conduct ponding tests to determine the rate reduction attrib-
utable to the linings. The results of these tests, as well
as the comparison with the pre-construction evaluation, are
included in Table 21. These results indicate that the linings
are not especially effective when the seepage rates are
already low.
Table 21. Comparison of seepage rates before and after canal
lining using ponding tests.
Canal Seepage rate Seepage rate Reduction
<-ctIiaj- before lining after lining
(cfd) (cfd)
Stub Ditch
Price Ditch
Gov't Highline Canal
Mesa County Ditch
Redlands First Lift
Canal
0.15
0.15
0.25
0.15
0.40
0.07
0.07
0.13
0.03
0.06
46.6%
46.6%
49%
76%
84%
The linings, in addition to reducing the operation and maint-
enance costs, also result in other direct benefits such as
reduced pumping costs. The moderate gradient channels, when
running near capacity from April 1 to October 31, experience
comparatively few problems with bank vegetation, mossing, and
sedimentation. Records and comments from irrigation compan-
ies indicate an average maintenance cost per mile of between
128
-------
$250 and $370 per year in the unlined sections, depending
on the canal size. In the intensive study area, the construc-
tion will probably result in a total savings of $2500 annually.
Although periodic maintenance is always necessary, there are
linings ten or more years old located throughout the valley
that have as yet required almost no attention. When the
canals are lined, the improvements to the delivery system
for new turnout structures and measuring devices greatly aid
control, distribution, and measurement of water, thereby pro-
viding a stimulus to irrigators for more efficient water man-
agement.
The local benefits from the linings in many parts of the Grand
Valley include factors such as improvements to adjacent lands.
In the test area and in a large portion of the valley, the
value of land is primarily determined by the expanding urban
areas and as such do not greatly depend on agricultural pro-
duction. Nonetheless, the increased utility of well drained
soils is demonstrated in the return to production when water
tables are controlled and the construction of basements in
homes where they were not possible before.
If the economics of salinity control are examined closely,
almost any control method is feasible on the basis of the
common benfit-cost ratio. The extension of the concept to
a basin scale yields some interesting ideas. The estimated
damages expected in Southern California from using an in-
creasingly saline water supply were reported to be about
$100,000 per ppm per year (6 ). If this figure is_added to
the authors' crude estimate of damages in the remaining
lower basin states and Mexico, a conservative value of
$150,000 per ppm per year at Lee's Ferry, Arizona is not an
unreasonable datum. In the period between 1931 and 1960
and adjusted to 1960 physical conditions in the basin, the
annual flow rate at Lee's Ferry was 10,880,000 acre-feet
and 8,570,000 tons of total dissolved solids (14). Thus±4
one ton of salt at Lee's Ferry corresponds to 0.67 x 10 ppm
and represents a damage of about ten dollars to the lower
basin. Other estimates have been around 7 dollars per ton,
but have not always considered the indirect costs. In terms
of economic feasibility, the cost of reducing one ton of
salt can at most cost, assuming a 50 year repayment period
at 7% interest, about $138. In order to show a benefit-cost
ratio of at least 1, this project should show at least a
4300 ton annual salt reduction from the test areas.
System Improvements
Although the formal results of canal and lateral lining will
be established in a later section, several qualitative
129
-------
statements relative to the importance of canal system
improvement can be made at this point. The first aspect
deals directly with the impact of better system management
on the salinity problem. Almost every arid agricultural
area depending upon an annually fluctuating water supply can
produce evidence to substantiate the fact that during periods
of diminished supply, farm production is often higher as a
result of better water management on the farm. The explan-
ation for this observation may not lie entirely in the use
by the farmer, but also in the attempts to equitably allo-
cate water among the irrigators. Thus, the irrigation com-
pany or district is the primary controller when faced with
water distribution among demands which totally exceed the
supply. Some evidence exists in the Grand Valley area to
support the contention that more efficient management of
water resulted in significant reduction in salt loading to
the river (16) . During the years, as shown earlier, when
the supply was inadequate to meet demands, the water was
"rationed" and more efficient use was made. The conclusion
therefore indicates that any presently proposed salinity
control alternative to be implemented on a valley-wide
scale must involve efficient canal management.
In order to improve canal system management, three types of
changes should be implemented: (1) system rehabilitation by
lining and installation of effective diversion and control
structures; (2) water measurement to each user; and (3) in-
stigation of call periods for demands. The results of incor-
porating these principles into the operation of a delivery
system would be a surplus of water at the river diversion
instead of at the canal turnout. Consequently, a large part
of the water which is presently flowing as field tailwater or
canal spillage could remain in the river. Two questions
would need consideration: (1) What incentive is there for
canal companies to leave the water in the river and risk
losing that portion of their right? and (2) What use would
be made of the surplus, and by whom?
Lateral System
As noted previously, the term "lateral" refers to the small
conveyance channels delivering water from company operated
canals to the cropland. During the early phases of this
study, the extent of the lateral system was not clearly
defined and the effects of laterals on the area hydrology
were underestimated. As a result, considerable reevaluation
was made to quantify the aspects of lateral system management
130
-------
Operation
When water is turned into the lateral system, it becomes
the responsibility of the users entitled to the diversion,
Single users served by an individual turnout are not
uncommon, but most laterals serve several irrigators who
decide among themselves how the lateral will be operated.
Most of the multiple-use laterals, which may serve as many
as 100 users, are allowed to run continuously with the unused
water being diverted into the drainage channels. This prac-
tice would be almost completely eliminated if the only water
diverted was that quantity appropriated to each acre in the
company water rights. The costs that would be passed on to
the irrigator for a more regulated canal system would also
provide added incentive for more efficient water management
practices below the canal turnout. Thus, there would be an
indirect economic incentive for better management.
There appears to be a considerable need for system rehabili-
tation in the form of linings and regulating structures prior
to placing restrictions on lateral diversions. The reason
is simply that little means of water distribution on an
equitable basis below the canal turnout exists. Aside from
the canal turnouts themselves, which could be rated individ-
ually, no observable means of measurement exists in the
intensive study area. Without adding control and measurement
structures, it would be impossible to either regulate lateral
diversions or distribute the water among users.
Lateral Seepage
Prior to undertaking the evaluation of seepage rates from
representative lateral sections, detailed maps of the system
in the study area, shown in Figs. 23, 24, and 25, were pre-
pared. From a review of the maps, several lateral sections
throughout the area were selected for study. The relatively
steep lateral grades in the north-south direction made
inflow-outflow measurements the most practical method for
measuring seepage rates. Small measuring flumes were
installed at the beginning and end sections of each lateral
under study, as well as all diversions in the lateral sec-
tion, or return flows to the lateral section. The dis-
charges were recorded for a period of about one day. The
losses were then evaluated from budgeting the water in the
isolated lateral reaches.
During the early stages of this effort, it became apparent
that the accuracy of the small Parshall flumes were the
limiting factor regarding the selection of lateral sections
131
-------
to be studied. The first aspect of the problem was that
seepage rates were low enough to be absorbed in the
-2-5% accuracy of the flumes unless lateral lengths of two
thousand feet or longer were used. The other problem encoun-
tered was that in several laterals a large number of field
diversions and field tailwater return flows occurred. In
such cases, the number of flumes required introduced consid-
erable uncertainty into the measurements and tended to
again mask the seepage losses within the -2-5% accuracy of
the flume. Consequently, the laterals served by the Stub
Ditch and Government Highline Canal had to be ignored, and
laterals under the remaining canals were carefully selected
before undertaking seepage rate evaluations.
The results of the seepage rate measurements for nine lateral
sections are tabulated in Table 22. The wetted perimeter of
these laterals ranged between three and five feet and was
characterized by large amounts of grass and weeds growing in
the channel. The capacity of the laterals was usually bet-
ween one-half and five cubic feet per second, and in most
cases, some problems with erosion have occurred as a result
of the grade. Some lengths throughout the area had already
been lined, but these did not represent a significant por-
tion of the total lateral length.
Results of Linings
Although no effort was made to evaluate seepage rates in the
laterals that were lined as part of this study in Area I, it
is not unrealistic to assume the same values as found for the
canal linings. A typical loss rate of 0.1 cfs per mile
would represent a rate in a usual lateral of about 0.5 cfd,
or about the same magnitude as earlier studies indicated.
Consequently, the lining of most laterals would result in
about a 80-90% seepage rate reduction.
A summary of the lateral linings constructed as part of this
project is included in Table 23 for comparison with the total
estimated lengths in the sections in the test area, a sample
of which was listed earlier in Table 14 for T1S, R1E. Obvi-
ously, only a small fraction of the system has been improved,
but even so the linings probably result in a seepage reduc-
tion on the order of 100-200 acre-feet annually. However,
it should be noted that the bulk of the linings were cons-
tructed above the Grand Valley Canal, where water tables are
relatively deep and thus experience somewhat higher seepage
rates than would be encountered in areas where water tables
are higher.
132
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Table 22. Results of lateral loss investigation.
u»
Canal Gate
Name No.
PD 168
164
151
GV 95
100
110
120
MC 46
70
Study length
(ft.)
2175
3620
1667
4910
2970
5000
5280
2600
3540
Length loss
(cfs)
0.
0.
0.
0.
0.
0.
0.
0.
0.
030
097
048
034
020
590
030
00
99
Length
3.
3.
7.
1.
2.
12.
1.
0.
18.
loss
8
6
4
5
6
3
0
0
0
Loss
9.
5.
23.
1.
4.
13.
1.
0.
26.
oer mile
11
27
46
61
62
0
0
0
82
Loss oer mile
(cfs)
0.
0.
0.
0.
0.
0.
0.
0.
1.
073
114
152
037
315
623
030
00
50
Design
Discharge*
(cfs)'
1.
2.
1.
2.
1.
5.
3.
3.
6.
00
50
00
00
00
00
50
00
00
*This value is inlet capacity consequently the design would need to be altered as diversions
are made along a length.
-------
Table 23. Summary of the sizes and lengths of laterals
lined during the project.
Description Length in Feet
14" trapezoidal 5,941
12" trapezoidal 11,435
10" trapezoidal 624
*6"xlO" rectangular 1,478
*12"xlO" rectangular 1,987
12" buried pipe 978
8" buried pipe 2,111
6" buried pipe 950
25,504
or
Total 4.83 miles
*First dimension listed in description refers to the bottom
width.
The benefits accrued from lining the lateral system in an
area like the Grand Valley are essentially the same as des-
cribed earlier concerning the canal linings. However, be-
cause of the vast extent of the lateral system in the prin-
cipal study area, the effect of the laterals is much greater
than canals. As with the canal system, the appurtenances,
such as the control and measurement structures, are an inte-
gral part of any lateral system improvements. Therefore,
the benefits derived from more efficient water management
cannot be ignored.
Again, the formulation of salinity control measures must
include, in addition to canal system improvements, lateral
improvements. In fact, the delivery system in general must
be rehabilitated, as well as undertaking improved operation
and management practices.
134
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SECTION X
EVALUATIONS OF THE FARM IRRIGATION SYSTEM
Without irrigation, the Colorado River Basin would not
support a productive agriculture, but the consequence of
irrigation is salinity. Water which percolates into the
ground water below the root zone carries with it not only
the salts in the irrigation water, but also salts that
were dissolved from the soil through which the water
passed. In addition, in the ground water basins below the
root zones further salt loadings are acquired. The result-
ing conclusion that the efficiency of on-farm water manage-
ment is the primary influence on total salt contributions
from an area must come as no surprise.
The efficiency of farm irrigation systems varies from
locality to locality, and it varies from year to year, or
even from irrigation to irrigation during the same year.
Although efficiency is influenced by such variables as
cost and quality of labor, ease of managing water, type of
crops being grown, and the characteristics of the soil, the
most important variable is the quantity of water available.
If water is abundant, its cost is usually low and there is
little economic incentive not to be wasteful to some degree.
The Grand Valley is a good example of a water-abundant area.
Its total water rights amount to a diversion of about 5
acre-feet per acre if the area within the irrigated boundar-
ies is considered, but almost 9 acre-feet per acre for each
irrigable acre in the valley.
In order to evaluate the pertinent variables for formulating
water and salt budgets in the intensive study area of this
project, it was necessary to conduct farm efficiency studies.
During the first irrigation season, three farms were selected
and data were collected concerning the inflows and outflows
on each farm. During the second irrigation season, soil
moisture measurements were included on four new farms, but
the work necessary to install the measuring devices and then
to monitor the water use on each farm spread project per-
sonnel too thin, and much of this study is inconclusive.
During the third and final season, experience with the prev-
ious two investigations proved extremely helpful. Two
farms were selected from the previous four and considerable
effort was made to collect all pertinent data. In addition
to the usual soil moisture measurements and inflow-outflow
determinations, soil samples were analyzed for salt so that
the effect of irrigation on salt movement in the soil profile
135
-------
could be roughly evaluated. Another short-term study con-
ducted was an advance-recession analysis to establish
distribution and application efficiencies.
The discussion provided in this section has been primarily
limited to the final efficiency evaluation because of its
completeness, but the data collected from the other efforts
and the experience derived from them was very helpful in
the periodic re-evaluation necessary to complete the study.
Description of Farms
The two farms in the intensive study area (Fig. 26) have
been referred to as the Martin and Bulla farms, respectively,
after the names of the owners whose cooperation made the
investigations possible. Both farms irrigate north to south
using 1-inch siphon tubes to divert water into the furrows.
A more detailed map of each farm, along with the instrumen-
tation employed, is illustrated in Figs. 46 and 47.
The Martin farm, consisting of 9.2 acres of field corn during
the 1971 irrigation season, is located between Eh Road and
U.S. HWY 6 & 24, and between 30 and 3Q% Roads. The 1-inch
siphon tubes that flow at a usual rate of about 7 gpm are
usually set for a run of about 24 hours, although it only
takes 6 to 7 hours to traverse the 1060 feet of furrows.
The additional time, while set mostly for irrigator conven-
ience, is used to apply what is thought to be the approp-
riate quantity of water. The corn crop on the Martin farm,
planted about the middle of May, was approximately 15 inches
tall by the first of July. In early August, the crop had
begun to tassel, and by the 15th of September it had matured
enough to be cut and sold for silage.
The Bulla farm, which was irrigated in the same manner as the
Martin farm, was comprised of 24.8 acres of corn and 2.7
acres of tomatoes. The length of run in the field varied
from 1160 feet in the tomatoes to 840 feet on the western
side of the corn field. Again, the set time was 24 hours,
but only 5 to 6 hours and 6 to 8 hours were necessary to
travel the lengths of the furrows in the tomatoes and corn,
respectively. Both the tomatoes and the corn were planted
in the middle of May. By the middle of August, the tomatoes
had essentially ripened, with the final picking on the 23rd
of August.
Both farms lie between the fruit areas in the eastern valley
and the sugar beet, grain, and corn areas predominant in
the western valley. The region is affected by the growing
136
-------
Driveway^
"bo co
C\J C\J
72' 0 213' 0 84'
£ In
in ":
(0 f°
o o
V
co
8 084'
78' 0 212'
I
1
, i
N
Access Tube;
03
-
t J 3" Parsha!) Flur
Martin Corn
Area = 9.2 acres
Scale I" = 200'
Fig. 46. Geometry and instrumentation of the Martin farm,
137
-------
CO
Bui la Corn and Tomatoes
Area = 29 2 Acres
9"Par8hall
\ Flume
8
-------
urban center of Grand Junction, where many residents of the
area have full time jobs . The farms are usually small ,
rarely exceeding 40 acres in one unit, and are often managed
by renters. The area is comparatively steep in grade and
the water tables are high in many places, so that productive
agriculture is very difficult to maintain. These factors
made the study farms, and in fact the entire project area,
attractive to study since the problems are as severe as any-
where in the valley. Thus, if feasible solutions can be
determined in an area such as this, which will amend the
salinity problem yet improve the agricultural conditions
for the water users, success would be assured in the other
less complicated problem areas.
Farm Efficiency
Farm efficiency is a general term relating to the effective-
ness of an irrigator in managing water from his canal turn-
out to the end of his fields and the bottom of his root zone
The components of farm efficiency include conveyance effi-
ciency, application efficiency, distribution efficiency, and
use efficiency, to mention a few. Conveyance efficiency is
defined as the percentage of water diverted from the canal
that is actually delivered to the farm. Application effi-
ciency may be defined as the percentage of water reaching
the farm that was stored in the root zone by the irrigation.
The term distribution efficiency relates to the uniformity
of irrigation. And finally, the use efficiency is the per-
centage of water reaching the root zone that is utilized
by the growing crops.
For the purposes of this report, two methods have been
selected to measure or indicate farm efficiency. These are:
(1) Application efficiency,
- 100 • •
3.
E = application efficiency
W = water either used by crop or stored in root zone
W = total water applied to the root zone
a
(2) Irrigation efficiency,
= 100 - ....................... (16)
5
139
-------
E- = irrigation efficiency
W = total water supplied to the farm
The only difference between the two efficiencies is that
the irrigation efficiency accounts for the field tailwater;
application efficiency does not.
The instrumentation and methods for evaluating these effi-
ciencies have been discussed in an earlier section, but it
may be helpful to the reader to reiterate the procedure in
this section.
The inflows to the farms and the outflows were measured with
small (6-inch) Parshall flumes equipped with continuous stage
recorders. The strip charts were then collected weekly and
the discharges determined. The flumes and recorders were
checked daily for clock timing and correct stage, and period-
ically the stilling wells were cleaned so the floats would
not stick in the silt deposited in the wells.
To measure the moisture in the root zone of the field, 2-in.
diameter aluminum tubes, each 6 feet long, were placed in
the field as shown in Figs. 46 and 47. The tubes were
installed in the row of the crop so they would not be dis-
turbed by tilling operations. These tubes became the centers
for soil sampling and neutron probe measurements. Soil
samples consisting of 1-foot core samples to a depth of five
feet were taken at a distance of approximately 1 foot from
the soil tube. Neutron probe readings were made inside the
tube and then correlated with the soil moisture analysis.
By proceeding in this manner, it was possible to monitor the
soil moisture levels at regular intervals with the neutron
probe.
The computation of evapotranspiration from the soil and
crop surfaces were made using the Blaney-Criddle method dis-
cussed earlier. The values of consumptive use are illus-
trated in Figs. 48 and 49 for corn and tomatoes in the
Grand Valley area. Since these estimates relate to water
consumption under conditions where adequate water is avail-
able in the root zone, the soil moisture levels were exam-
ined to see if these conditions were always met.
The results of the 1971 irrigation season study of the two
farms are tabulated in Table 24. These data are for the
average field condition, and it should be noted that a
leaching requirement has not been included in this analysis.
The pre-irrigations in the spring have not been included
in this analysis since the project personnel were not able
to install the instrumentation until after the crops had
been planted.
140
-------
10.0
0
Consumptive Use Curves
for Corn During
Summer of 1971
April
May
June July
Time, Months
August
Sept.
Fig, 48. Potential consumptive use rate for corn in the Grand Valley area.
-------
10.0
April
May
June July
Time, Months.
August
Consumptive Use Curves
for Tomatoes During
Summer of 1971
Sept
Fig. 49. Potential consumptive use rate for tomatoes in the Grand Valley area,
-------
Table 24 . Results of 1971 farm efficiency investigations.
Irrigation
Period
Total
Inflow
(in)
Net
Applied
(in)
Bui la Tomatoes
4/16-5/20
5/31-6/22
7/20-8/10
8/17-8/23
Bulla Corn
6/9-6/22
7/7-7/16
7/20-7/28
8/4-8/13
Martin Corn
6/16-6/26
7/6-7/29
8/3-8/13
8/13-8/24
22.2
9.65
9.62
8.72
5.00
7.13
8.25
8.00
12.70
12.84
5.85
5.97
16.05
6.08
5.66
8.44
3.53
4.02
6.02
4.79
8.91
6.18
2.97
3.38
Soil Moisture
(in)
Begin
Period
11.1
15.7
16.8
16.1
17.7
17.7
16.7
17.1
16.5
19.2
15.2
15.8
End
Period
18.1
16.5
17.5
17.7
20.4
17.6
18.2
17.6
16.7
16.4
15.8
16.6
Change
in
Storage
(in)
+ 7.0
+ 0.8
+ 0.7
+1.6
+ 2.7
-0.1
+ 1.5
+0.5
+0.2
-2.8
+0.6
+ 0.8
Consump
Use
(in)
0.06
3.11
4.84
0.96
0.83
1.39
1.40
1.39
0.94
3.78
1.91
1.29
Deep
Percolation
(in)
8.99
2.89
0.12
5.88
0.0
2.73
3.12
2.90
7.77
5.20
0.46
1.29
Application
Efficiency
(%)
50.2
52.5
97.7
30.2
100.0
32.1
48.1
39.5
12.8
15.8
50.9
61.9
Irrigation
Efficiency
(%)
36.3
33.1
57.6
29.2
70.6
18.1
35.2
23.6
9.0
7.6
25.8
35.0
CO
-------
The pattern of irrigation does not seem to change a great
deal througn the season in terms of amounts applied and
this makes efficiencies earlier in the irrigation season
tend to be somewhat lower than later in the season. The
important item in Table 24 is the amount of deep percola-
tion. Under both farm operations, considerable loss was
encountered.
Effect of Irrigation Practices on Farm Efficiency
After having measured the efficiencies on several farms dur-
ing the study period, it was decided to investigate the
effect on efficiency that could be expected from different
irrigation practices. Since salt loadings are so highly
dependent on irrigation efficiencies, the results are an
integral part of a salinity control study.
The primary effort in this regard was an advance-recession
analysis conducted on both farms near the end of the irriga-
tion season. It should be mentioned that the tests were
only conducted once on each farm and thus only indicate the
irrigation conditions during the period of the tests.
Nevertheless, a qualitative discussion is possible.
The procedure was to select four furrows in which four
stream sizes would be diverted. At the inlet and the outlet
of the furrow, a WSC 60°V-shaped flume was installed to
measure these flows. Then, flumes of the same nature were
placed every 100 feet in the furrow between the furrow
inlet and exit. The procedure was then to start the flow
in the 1-inch siphon tubes and time the advance from
station to station along the furrow. When the discharge
at the outflow had stabilized, the flow was cut and the
recession from station to station was measured. The res-
ults have been plotted for the two farms according to the
advance curves at various stream sizes in Figs. 50 and 51,
and by recession rates in Figs. 52 and 53.
In Fig. 50, the curve representing 27 gpm is noted to fall
below the 30gpm curve. The reason for this occurrence is
that during the experiment, it was decided that a flow rate
between 30gpm and 16gpm should also be run. Unfortunately,
the furrow had already been wetted and the results are non-
representative. However, the test does indicate the effects
of precipitation, or a recent irrigation, or possibly the
results of a cutback method of irrigation.
From the advance-recession data, two measures of farm effi-
ciency were evaluated. The first of these is the field
144
-------
Ul
500 r-
Furrow Advance Curves
Bui la Farm August 27, 1971
Grand Junction, Colorado
5* 6* 7* 8* 9*
Station Numbers, Ft.
10+ II*
Fig. 50. Advance rate of furrow streams on the Bulla farm.
-------
200
150
0>
c
2
: 100
50
Furrow Advance Curves
Martin Farm August 26, 1971
Grand Junction, Colorado
0*00
2*00
4*00 6*00 8*00
Station Numbers, Ft.
10*00
Fig. 51. Advance rates of furrow streams on the Martin farm.
-------
Furrow Recession
Bullo Farm August 27 1971
Grand Junction, Colorado
20 h
2*00
4*00 6*00 8*00
Station Numbers, Ft.
10*00
12*00
Fig. 52. Recession rates of furrow streams on the Bulla farm.
-------
ou
40
30
in
.1
2
P
20
10
Furrow Recession
Martin Farm August 26, 1971
Grand Junction, Colorado
-
- /
/ I
-H
f~ $
• r/
'/ /
// ^
if r^
,7 /
i
<
III
1 '
/
./
w
/
O1
I
I
2+00 4+00 6+00 8+00 10+00
Station Numbers, Ft
Fig. 53. Recession rates of furrow streams on the Martin farm.
148
-------
distribution efficiency, which is the percentage of the
average depth of water infiltrated in the field to that
which is infiltrated at the end of the field:
D,
100
Ed =
D
(17)
u
in which
D
J
D
= distribution efficiency
= depth infiltrated at lower end in inches
= depth infiltrated at upper end in inches
The second efficiency is called application efficiency, as
in the preceding discussion, except that it is defined as
the percentage of the total depth applied that is repres-
ented by the average field infiltration:
DT)/2
(D
Ea =
u
D
where
E = application efficiency
a
96.3
Q
D =
AREA of furrow
(18)
(19)
in which T = time of irrigation in hrs.
Q = furrow flow rate in gpm
Selected data and analysis have been included in Table 25 for
observation of the results. Although some of the data could
not be analyzed, it was possible to establish that a uniform
application, and in the desired quantity, could be incorpor-
ated in the irrigation practice. This would be the first
step in a more efficient on-the-farm water management program
which would greatly reduce the salinity problem.
Effect of Irrigation on Soil Salts
Many of the soil samples collected to measure soil moisture
were also used to measure the salts in the soil profile.
Every sample analyzed for salt was measured for pH, speci-
fic conductance, calcium, magnesium, and sodium. Rotating
sets were also analyzed for complete constituent breakdown.
The purpose of performing chemical analyses on the soil
samples was to see if the effects of different irrigation
practices could be observed on the salts in the soil.
149
-------
Table 25. Advance-Recession Analysis.
en
o
Q
(gpm)
Distribution
Ta Tad
(min) (min)
Efficiencies
Ta-Tad ,.U»
DL
(in)
Ed
Bulla Farm
30
27
30
27
30
27
Martin
30
12
30
12
30
12
1200
1200
900
900
600
600
Farm
1200
1200
900
900
600
600
174
122
174
122
174
122
30
77
30
77
30
77
1026
1078
726
778
426
478
1170
1123
870
823
570
523
13
14
12
13
10
12
4
6
3
6
3
6
.9
.1
.5
.6
.9
.9
.2
.8
.8
.6
.2
.4
13.1
14.0
11.6
13.1
9.6
12.1
4.1
6.7
3.7
6.5
3.1
6.2
97.0
99.6
96.2
98.3
93.6
96.6
98.8
99.4
98.6
99.3
98.5
98.5
Application
Q Ta
(gpm) (min)
Bulla
30
27
30
27
30
27
Martin
30
12
30
12
30
12
Farm
1200
1200
900
900
600
600
Farm
1200
1200
900
900
600
600
Efficiencies
D Ea
(in) (%)
20.5
18.4
15.4
13.9
10.3
9.2
24.2
9.65
18.1
7.35
12.1
4.84
66.0
76.4
78.3
96.4
99.6
100.0
17.1
70.0
20.7
89.1
26.0
100.0
-------
Two aspects of salt movement in the irrigated soils pertin-
ent to this study are the total salt content of the soil
with respect to time and depth, and the activity of sodium.
The procedure used to evaluate these parameters was stand-
ard soil salt analyses employed by the Colorado State Uni-
versity Soil Testing Laboratory. The soil samples were
collected and evaluated for moisture content. Then, the
water sample was extracted (saturated extract) by applying
fresh water to the soil and then removing it by suction.
This procedure has a tendency to collect not only the salts
previously carried by root zone moisture, but also to
remove some ions from the soil particles themselves. Con-
sequently, the similarity between the salt movements in the
soil and these data may be questionable in terms of highly-
complex reactions that take place in the soil profile during
the action of irrigation.
The effect of irrigation in the soil profiles of the two
efficiency farms on the total salts has been successfully
monitored by measuring the specific conductance of the water
sample taken from the soil samples. In Fig. 54, the speci-
fic conductance through the soil profile for data collected
on the Martin farm is presented. The sample taken on July 6,
1971 probably represents the general condition in a well
watered soil in the area, since the specific conductance
varies from about 1500 iamhos/cm at the surface to about
3000 pimhos/cm at a depth of 5 feet. This typical soil con-
dition, if indeed it is truly representative, would require
a leaching requirement of about 20-30 percent. The samples
taken on June 10 and June 16 seem to point out the effect of
a pre-irrigation in the spring. The irrigation seems to
have been sufficient to distribute the salts in a steadily
increasing concentration as the depth in the profile is
increased.
The data from the Buila farm samplings, shown in Fig. 55,
have been plotted against time to show the seasonal fluctua-
tion within the various depths of the root zone. All of
these lines show the effect of the irrigation between June 16
and June 22, during which time very little water deep per-
colated out of the root zone. On the other hand, the meas-
urements made on August 3 are shown to be influenced by the
high percolation rate during the period of July 20 to July 28,
Two additional graphs, essentially in the same format only
indicating the activity of the sodium ion, have been included
and are illustrated in Figs. 56 and 57.
During the advance and recession study, the question of water
quality degradation resulting from tailwater runoff from
croplands was examined. Samples were taken at the head of
151
-------
! '
' n
' •
..-,
0)
• )
' »
Martin Farm
6 - 10-71
6 - 16-71
7 - 6-71
8 • 3-71
9 - 2-71
1000 2000 3000 4000 5000 6000 7000
Specific Conductance fimhos/cm
8000
9000
10000
Fig. 54. Specific conductance versus depth plot for the chemical analysis of the soil
moisture samples on the Martin farm (samples were saturated extracts).
-------
9000
8000
7000
en
o
E 6000
a
u
§
o
50OO
C
a>
4000
3000
2000
Fig. 55.
June
Bulla Farm
3 feet
2 feet
field average
5 feet
foot
July
August
Specific conductance for various soil depths during the
1971 irrigation season on the Bulla farm.
153
-------
0
"I
,1.
0)
o 2
o f-
VI
V
m
13
Q
-------
500
400
•
300
200
100
Bui to Farm
8 feet
feet
field average
foot
June
July
August
Fig. 57. Change in sodium concentration through the irrigation season on the Bulla farm.
-------
each furrow and then periodically at the bottom of the field,
The results indicate very little degradation, while the
small amount of salt pick-up vanishes with time as the field
tailwater continues to flow.
156
-------
SECTION XI
EVALUATIONS OF THE GROUND WATER SYSTEM
Because of the salt yielding characteristics of soils and
aquifers in the Colorado River Basin, the distribution and
quantity of ground waters have a profound influence on
regional salinity conditions. In much of the basin, the
primary source of ground water is deep percolation losses
from inefficient irrigation practices and seepage from
conveyance systems. A notable example is the Grand Valley
in which a large salt load is added to the system almost
exclusively from irrigation return flows. The ground water
conditions are also of utmost concern to the local farmers
who can make little productive use of lands where the
highly saline water tables are too near the surface. It
is thus apparent that the control of ground water flows by
careful water management, efficient irrigation practices,
and adequate drainage is both a local and regional salin-
ity control alternative.
The land on the north side of the Colorado River in Grand
Valley drains from north to south along the natural grade.
The low lying lands adjacent to the river must convey not
only irrigation return flows from these areas, but also the
flows from all higher lands to the north. The result is a
noticeable decline in agricultural productivity towards the
river as the natural drainage capacities are exceeded and
a high water table occurs. In this investigation, the
scope of ground water examination has been limited to the
saturated area between the water table and the top of the
Mancos Shale.
The similarity between the intensive study area utilized
in this research effort and most of the valley is thought
to be quite good. Other investigations in the western
valley have established the ground water conditions in that
area The discussion in this section can therefore be
centered primarily on Area I. The conclusions regarding
salinity management are also thought to be fairly represen-
tative of the valley.
Soil and Aquifer Characteristics
An evaluation of the basic characteristics of the subsurface
157
-------
in examining the ground water system. In Grand Valley, the
structure of the substrata makes it convenient to examine
the cobble aquifer and the overlying soil individually. The
interaction of these two flow regions is probably the most
critical factor influencing the design of either a salinity
control project or a drainage system. Water in both areas
comes primarily from deep percolation from over-irrigation,
as well as canal and lateral seepage losses. Between the
soil and the cobble aquifers there exists an intermittent
clay layer having a very low hydraulic conductivity (0.0001
in/hr), which restricts the flow between the two regions
primarily to areas where holes or thin spots exist in the
clay layer. Ground water above this confining layer may
not be the only source of water in the cobble, since the
cobble strata only extends part way up the northerly cross
section of Area I.
The holes or thin spots in the confining clay strata may
allow either an upward or downward movement of water through
the clay layer. When artesian conditions exist in the cob-
ble, upward movement of water into the soil zone may result
in local areas of severe waterlogged conditions, with assoc-
iated visible salinity problems. On the other hand, downward
movement into the cobble may occur, with good drainage being
evident as the flow in the cobble is much less restricted
than in the soil above.
Soil Characteristics
A great deal of work was performed in Area I to establish
the characteristics of the soil profile below the water
table. The first effort was the installation of the 3/8
inch steel pipe piezometers discussed earlier. During the
process of installation, it was possible for the man holding
the pipe to feel the changes in soil texture as the pipe was
jetted downward. Lenses of small gravel and the periodic
clay layer were especially noticeable. Since numerous pie-
zometers were placed throughout the area, it was possible to
locate the more obvious strata in the test area. In addi-
tion, since it was impossible to extend the pipe beyond the
confining clay layer, the upper surface of the cobble aqui-
fer was also located. A typical profile resulting from the
logs of this work was illustrated earlier in Fig. 8.
Once the piezometers had been installed, periodic water
level measurements were made in each tube, which indicated
the pressures through the soil profile. The piezometers,
which protruded only a short distance below the water levels
in them, were assumed to be good indicators of the water
table elevation. In order to give the reader some idea of
158
-------
the magnitude of the changes in the ground water conditions,
data prior to the irrigation season, along with that collec-
ted during the peak of the irrigation season, have been pic-
torially represented in Figs. 58 and 59, respectively.
As pointed out previously, the vertical hydraulic gradients
in the ground water basin indicate the movement of the water.
The piezometer clusters were installed to determine these
gradients. The data collected thus far indicate little or
no artesian condition in the test area, as was found in the
western valley studies reviewed earlier. This would indi-
cate that drainage from the soils is taking place into the
cobble aquifer. Thus, the high water table conditions in
the area ranresent an overloading of the natural drainage
capacity.
Since the ground water return flows to the river proceed
from north to south, the piezometers were also used to
evaluate the horizontal hydraulic gradients, which are the
driving forces causing the flows to occur. During the two
periods illustrated in Figs. 58 and 59, the weighted average
horizontal gradients were 0.00899 ft/ft and 0.00939 ft/ft,
respectively. The relatively small changes between the two
periods, along with the comparison of the magnitudes of
vertical gradients, again indicate the primary movement in
the soils to be downward.
The piezometers were also utilized to measure hydraulic con-
ductivity according to the method outlined in SECTION VII.
The results of this analysis, tabulated in Table 26, show
a low permeability in the soils. It has been well estab-
lished that soil permeability is highly affected by the
sodium ion concentration present in the soil solution. It
seems justifiable to conclude from the analysis presented
in SECTION VIII that the relatively high proportions of
calcium and magnesium ions found in ground water samples
have resulted in some improvement in the soil structure,
thereby causing these conductivities to be greater than in
high sodium areas.
Cobble Aquifer Characteristics
The conditions in the cobble strata were monitored during
the study with 2-inch wells drilled into the layer. Tests
from previous investigations noted earlier, along with
limited data from this effort, indicate an average value
of hydraulic conductivity on the order of 40 inches per
hour, or about 4000 times as permeable as the soil and
about 400,000 times as much as a typical value for the con-
fining clay stratum. The drillers log for the 1951 test
159
-------
Stub Ditch
Government
Hghline
Canal
a
c
b
d
a-Water Table Elevation
b—Water Depth Below Surface
c—Aquifer Pressure Elevation
d— Average Profile Vertical Gradient
(+ Downward)
-
Mesa County Ditch
Scale I Mile
Fig. 58. Water table elevations, below surface depths, average vertical gradients, and
cobble pressures for selected stations in Area I during March 1971.
-------
itub Ditch
Government
Highline
Canal
a
c
b
d
a - Water Table Elevation
b-Water Depth Below Surface
c— Aquifer Pressure Elevation
d— Average Profile Vertical Gradient
(+ Downward)
Mesa County Ditch
Scale I Mile
Fig. 59. Water table elevations, depths below soil surface, average vertical gradients,
and cobble pressure elevation for selected stations in the test area during
July 1971.
-------
Table 26. Results of hydraulic conductivity measurements from
piezometers in Area I.
Location
D - 28.5
D - 29
D - 30
D - 31
D - 32
E - 29.5
E - 30
E - 30.85
E - 31.5
E - 32.3
F - 30
F - 30.5
F - 31
F - 31.5
F - 32
FS - 30.5
FS - 31
FS - 32
Depth, ft.
9
14
18
10
10
10
18
12
15
15
21
35
39
42
14
21
32
42
14
21
39
21
37
45
21
35
43
16
23
22
35
47
50
61
15
21
25
14
21
35
41
14
29
K, in/hr.
0.001
0.013
0.005
0.005
0.003
0.025
0.00375
0.0118
0.017
0.017
0.002
0.001
0.003
0.002
0.003
0.002
0.001
0.0013
0.007
0.002
0.062
0.002
0.0018
0.011
0.002
0.017
0.0006
0.011
0.025
0.0006
0.003
0.013
0.0025
0.0007
0.0015
0.001
0.0035
0.0004
0.003
0.00035
0.0032
0.0205
0.0013
162
-------
well, shown in Fig. 10, is quite similar to the logs of the
2-inch wells drilled in Area I, except that the cobble in
Area I seemed to have a greater percentage of large rocks.
In fact, this material is very similar to the boulders in
the river channel, which can be observed during low flow
periods. It would be the unqualified opinion of the writers
that the cobble aquifer originated from river bottom deposits
An examination of hydraulic pressures in the cobble during
the same periods indicated for the piezometers reveals that
a somewhat greater fluctuation with time occurs. During the
spring period, the horizontal gradient in the area was
0.00983 ft/ft, while the gradient during the irrigation per-
iod was 0.0104 ft/ft. Thus, it is quite clear that the vast
majority of subsurface return flows are taking place through
the cobble aquifer.
Ground Water Management
The capability of controlling ground water flows has always
been a necessary prerequisite in an irrigated area. The
fact that the drainage in the Grand Valley is presently
inadequate in the areas most affected near the river is
unquestionable. But recently, the need for controlling irri-
gation return flows has become of primary concern from a
salinity control standpoint to the valley.
In order to control the salt pickup from the Grand Valley
the subsurface return flows through the cobble aquifer and
the overlying soils must be reduced. It has been argued
that even reducing ground water flows would not reduce the
salt loadings because the reduced flow through the aquifer
would simply become more concentrated and thus carry the
same salt load. The results of this study indicate that
ground water is retained in the soils and aquifer much longer
than is necessary to reach chemical equilibrium with ambient
salinity concentrations in the subsurface formations. Con-
sequently, the writers feel that a reduction in deep percol-
ation losses will result in a decreased salt loading reaching
the Colorado River. However, whether a 50 percent reduction
in moisture movement through the soil would result in a 50
percent reduction in salt pickup is not known at the present
time.
The exact region of salt pickup through the soil profile and
aquifer has not been sufficiently defined in this study.
It was originally thought that when water came in contact
with the Mancos Shale, the most significant load of salts
was picked up. Since many of the soils seem to originate
163
-------
from the shale, the nature of the salt loading in the area
is unclear. Studies should be undertaken to define the
specific nature of water movement and associated chemical
changes before the final assessment of salinity control
alternatives is made. The results of such a study may pos-
sibly indicate that a field drainage system which intercepts
the water before it percolates into the ground water basin
may be a sound salinity control measure, since it would
reduce the contact time of deep percolation and seepage
losses in the soils.
164
-------
SECTION XII
WATER AND SALT BUDGETS
Although seepage measurements before and after the linings
were all that was necessary to determine the resulting seep-
age reduction, evaluation of the linings relative to the
total system required accounting for the water and salt
flows. In this manner, the relative magnitude of the seg-
mented flow system could be evaluated and an indication of
the importance of conveyance seepage flows could be given
in relation to the other components of the irrigation and
drainage network. This budgeting procedure has the poten-
tial for establishing the possibility of controlling salin-
ity at other locations within the agricultural system.
The hydro-salinity flow system can be divided into an exam-
ination of the water and salt flows, even though the salt
flow occurs within the water transport network. One com-
pletely independent part of the salinity system is the salt
pick-up from soils and subsurface contacts.
This section will be presented and discussed in three parts:
(!) Review of water budget computations
(2) Review of salt budget computations
(3) Analysis of budgeting results
Water Budget Calculations
The computation of the water budgets is the first essential
in hydro-salinity modeling because salt flows and water
quality in general are dependent on the quantity and distri-
bution of water in the hydrologic system. In all but the
most limited cases, water budgeting requires some adDustment
to formulated data in order to compensate for instrumentation
limitations, data accuracy, and interaction among variables.
As noted previously, a comparison of mass balance and direct
calculation methods was made on ground water flows as a
basis for model refinement. It seems justified to ^c^
that this procedure gives an additional degree of confidence
to the results.
The first step in computing the budgets was to evaluate the
distribution of the water before it reached the root zone.
Water is initially diverted from the two rivers into the
various canals from which a small percentage is lost by
165
-------
seepage, some is spilled into washes or drains in order to
regulate capacity, and the bulk is diverted into the field
lateral system. In the lateral network some of these flows
are lost by seepage and the rest is applied to the cropland.
In the Grand Valley irrigation system a large proportion of
the field application eventually reaches the drainage system
as field tailwater, and the final component enters the root
zone for crop use.
Once in the root zone, opportunity exists for consumptive
use by crops. Under optimum conditions, the water used from
the root zone will approximate the crops' potential demand.
Potential evapotranspiration from cropland surfaces in Grand
Valley was computed using the modified Blaney-Criddle formul-
ation. A summary of the calculations according to each canal
system is shown in Table 27. These data were also derived
for all potential water uses in the valley and have been tab-
ulated in Table 28. The excess water in the root zone that
cannot be retained in storage percolates through the soil
profile until it reaches the ground water. Since the water
table is not always at the bottom boundary of the root zone,
a region of flow between this boundary and the water table
should be considered. For purposes of this study, this
region (soil profile) was initially assumed completely sat-
urated and disregarded.
The ground water additions are comprised of canal and lateral
seepage and deep percolation from excessive irrigation.
Occasionally, the amount of precipitation is sufficient to
account for some inflows to the ground water system. A pro-
portion of ground water is either intercepted by the drainage
system or transpired by phreatophytes. It was assumed here
that phreatophytes use water at their potential rate and use
all precipitation that falls on these acreages. Because of
the fluctuating nature of the ground water additions, the
storage within the ground water basin also varies significantly
throughout the year. In budget computations, a negative stor-
age change indicates that more flows are leaving the subsur-
face basin than are entering. The remaining water is forced
to flow towards the river by the hydraulic gradients acting
on the water from elevation differences in the local topo-
graphy. These flows were referred to in the model as the
total ground water outflows and were then used to evaluate
the performance of the entire model.
Salt Budget Calculations
Although the salinity flow system generally follows the water
flows, there are three additional complicating factors that
166
-------
Table 27.
Potential cropland demand in the Grand Valley by canal system serving
the land. (units in acre-feet)
Canal System
Stub Ditch
Government Highline
Canal
Price Ditch
Grand Valley Canal
Mesa County Ditch
Adjacent to River
Orchard Mesa #1
Orchard Mesa #2
Red lands
Total
Apr
70
1,800
480
2,120
120
30
480
420
340
5,860
Month
May
160
5,230
1,160
5,840
290
70
1,170
960
780
15,660
Jun
320
13,130
2,380
14,040
610
180
2,470
1,780
1,450
36,360
Jul
350
14,580
2,560
14,980
660
200
2,800
2,010
1,710
39,850
Aug
250
11,000
1,850
11,440
480
140
2,060
1,390
1,220
29,830
Sep
160
6,970
1,190
7,090
300
90
1,330
900
790
18,820
Oct
90
8,380
670
6,230
180
50
780
510
210
17,100
CTi
-------
Table 28. Potential evapotranspiration demand of the Grand Valley.
(units in acre-feet)
en
oo
Water Use
Irrigated
Cropland
Domestic*
Use
Evaporation
Phreatophyte
Consumption
Total
Month
Apr
5,860
1,410
640
4,330
18,240
May
15,660
3,020
1,320
9,430
29,430
Jun
36,360
5,050
2,190
18,610
62,210
Jul
39,850
6,010
2,610
25,100
73,570
Aug
29,830
4,360
1,900
19,910
56,000
Sep
18,820
3,000
1,360
14,540
37,720
Oct
17,100
1,640
820
7,920
27,480
*Assumed 65% consumed.
-------
must be considered. The first of these is the ion exchange
process that occurs in the root zone. Because the scope of
this project did not allow for such an extensive examination,
this factor was ignored. It should be emphasized that this
information is very important to understanding salinity
problems in agricultural areas.
The second aspect that must be considered is the quantity of
salts actually imparted to the water from the soils them-
selves. The distribution of this "pick up" quantity is not
known and was assumed to occur only in the ground water
basin. This conclusion is obviously false, but does not
interfere with the scope of this modeling effort. Again,
the knowledge of where the salt is being added is of the
utmost importance to salinity control planning. For exam-
ple, if it were known that little salt is actually added
in the root zone, then the interception of deep percolation
by a system of field tile drainage would be a feasible
salinity control alternative.
The third and final component of the independent variables
affecting salt movements is related to the salt and water
storage changes that occur within the ground water basin.
When a large influx of water is added via deep percolation
or conveyance seepage, this water has not as yet picked up
much salt due to the short time it has been in contact with
the soils. As a result, the large storage increases in the
spring and early summer result in only small salt flow to
the ground water basin. On the other hand, when large
storage decreases occur in the late fall and early winter,
a relatively large salt depletion occurs from the system.^
These negative storage changes were found from water quality
data to be on the order of 2-3 times the salt movement as
compared with the positive ground water storage changes.
This particular parameter regarding the salinity flow was
handled in the salinity phase of the model.
Water and Salt Budgets
The water and salt budget summaries recorded in this section
represent both the pre-construction evaluation (1969 water
year) and the post-construction study (1971 water year).
Data collection and supplementary studies were continued
during the interim 1970 water year, but formal budgeting
was not calculated.
Numerous considerations such as improved experience, more
comprehensive testing, and better project facilities, com-
bined during the course of this investigation to modify
169
-------
certain conclusions. In addition, a clearer understanding
of the overall valley hydro-salinity mechanism was gained,
so a better basis for suggesting salinity management alter-
natives can be presented. The results of these general
improvements were several changes in the water and salt bud-
get items that will be explained in the following pages.
Because of the large page requirements for a typical water
or salt budget, the presentation herein has been partitioned
into the flow system before and after distribution within
the root zone. Certain computational steps have been omitted
from the results and, if the reader has difficulty following
the data breakdown, it is suggested that Section VI be
reviewed.
Water and Salt Inflow Distribution in Area I.
The first part of the water and salt budgets has been included
for the 1969 and 1971 water years in Tables 29, 30, 31, and
32. Although a significant year-to-year variation in the
magnitude of water and salt flows is expected, several changes
have occurred as noted previously from better experimental
evidence. Notable among these modifications are the increase
in average area farm efficiency resulting from an improved
farm efficiency study, a large increase in the magnitude of
lateral seepage losses as a result of closer examination of
these flows, and somewhat different values of ground water
changes and salt flows that have resulted from more exten-
sive data. For example, the water quality data used in prep-
aring the 1969 budget were taken from only a few field meas-
urements and tend to be higher than the 1971 data, which more
closely paralleled the data on the river stations.
Ground Water and Salt Flows
Water and salt movements beneath the soil surface include
evapotranspiration and drainage return flows, tabulated in
Tables 33, 34, 35, and 36. These data also reflect some
model improvements that were made, particularly in the salt
flow system and the ground water model. For example, the
1969 budgets are based upon a ground water model consisting
of three strata, whereas the 1971 model was limited to two
because the flows in the tighter clay strata can be neglec-
ted. In addition, the salinity segment of the model was
modified to compensate for the discrepancies found in the
salt flows associated with storage change in the ground
water basin as discussed; and the salt pickup and ground
water salt storage changes have been separated for the 1971
budgets to allow for clearer understanding of the budgets.
170
-------
Table 29- Water budget inflows to Area I during 1969 study period.
(all units in acre-feet)
PRECIPITATION
Month
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
cropland
200
130
130
130
180
180
180
130
130
130
240
200
phreat.
40
30
30
30
40
40
40
40
40
40
50
40
CANAL DIVERSIONS
seepage
120
0
0
0
0
0
120
120
120
120
120
120
spillage
1200
0
0
0
0
0
2000
2000
2000
2000
2000
2000
lateral
diversions
2050
0
0
0
0
0
2920
3900
4510
4800
4410
3220
LATERAL DIVERSIONS
seepage
80
0
0
0
0
0
120
120
120
120
120
120
tailwater
1200
0
0
0
0
0
980
1600
1600
1600
1500
1500
root zone
diversions
770
0
0
0
0
0
1820
2180
2790
3080
2790
1600
ANNUAL 1960
460
840
13200
25810
800
9980
15030
-------
Table 30. Water budget inflows to Area I during 1971 water year.
(all units in acre-feet)
to
PRECIPITATION
Month
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
cropland
420
120
100
140
10
470
200
0
240
160
120
210
phreat.
130
40
30
40
10
150
70
0
80
50
40
70
CANAL DIVERSIONS
seepage
30
0
0
0
0
0
30
30
30
30
30
30
spillage
1200
0
0
0
0
0
2000
2000
2000
2000
2000
2000
lateral
diversions
2600
0
0
0
0
0
2800
3960
4460
4830
4070
3230
LATERAL DIVERSIONS
seepage
270
0
0
0
0
0
260
370
420
460
380
290
tailwater
1350
0
0
0
0
0
860
1220
1370
1460
1400
1350
root zone
diversions
980
0
0
0
0
0
1680
2370
2670
2910
2290
1620
ANNUAL 2190
710
210
13200
25980
2450
9010
14520
-------
Table 31. Salt budget inflows to Area I, in tons of total
dissolved solids, during the 1969 water year.
Canal salt diversions
MO
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
seepage
110
0
0
0
0
0
160
160
160
110
110
110
spillage
1890
0
0
0
0
0
2720
2720
2720
1900
1900
1900
lat.
div.
1950
0
0
0
0
0
4000
5300
6130
4570
4200
3070
Lateral salt diversions
seepage
70
0
0
0
0
0
160
160
160
110
110
110
tail water
1140
0
0
0
0
0
1340
2170
2180
1530
1440
1440
root zone
diversions
740
0
0
0
0
0
2500
2970
3790
2930
2650
1520
ANN.
920
15750
29220
880
11240
17100
173
-------
Table 32. Salt budget inflows to Area I, in tons of total
dissolved solids, during the 1971 water year.
Canal salt diversions
MO
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
seepage
30
0
0
0
0
0
10
20
20
30
30
30
spillage
1890
0
0
0
0
0
2720
2720
2720
1900
1900
1900
lat.
div.
2540
0
0
0
0
0
1520
2690
3640
4600
4430
3080
Lateral salt diversions
seepage
260
0
0
0
0
0
140
250
340
440
410
280
tailwater
1280
0
0
0
0
0
460
820
1110
1390
1520
1280
root zone
diversions
1000
0
0
0
0
0
920
1620
2190
2770
2500
1520
ANN. 170
15750
22500
2120
7860
12520
174
-------
Table 33.
Water budget ground water flows in Area I
during the 1969 study period. (all units in
acre-feet)
Root Zone
Diversions
MO
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
cropland
use
460
130
70
0
0
0
680
920
1670
2000
1820
1140
deep
perc.
510
0
60
130
180
180
1320
1390
1250
1210
1210
660
drainage
flows
200
180
150
120
70
60
300
300
300
300
250
500
Ground Water Flows
phreat.
use
200
40
30
30
40
40
300
310
330
350
400
280
storage
change
-100
-560
-400
-300
-200
-200
600
540
300
200
200
-100
subsur .
outflow
450
370
310
310
310
320
400
520
600
640
650
560
ANN.
8890
8100
2430
2350
- 20
5440
175
-------
Table 34.
Water budget ground water flows in Area I
during 1971 study period. (all units in
acre-feet)
Root Zone
Diversions
MO cropland
use
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
ANN.
490
50
0
0
20
130
310
760
1620
1780
1330
860
7350
deep
perc .
910
70
100
140
0
330
1570
1610
1290
1290
1080
970
9360
drainage
flows
290
240
180
150
90
100
140
190
240
260
310
300
2490
Ground Water Flows
phreat .
use*
300
70
0
0
10
80
280
460
590
700
470
330
3290
storage
change
100
-700
-450
-350
-450
-250
1000
800
300
150
0
0
150
subsur.
outflow
520
460
370
340
350
400
440
560
610
670
710
660
6090
*adjusted for precipitation
176
-------
Table 35,
Ground water salt flows in Area I, in tons of total dissolved solids,
during the 1969 water year.
Root Zone Salt Budget
MO
salt accumulated salt add.
depository
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
ANN.
630
190
120
40
50
50
1330
1670
2720
2240
2110
1350
12500
storage
0
190*
0
0
0
0
0
0
0
0
0
0
190
to G.W.
740
0
310
40
50
50
2500
2970
3790
2930
2650
1520
17550
Ground
total salt pickup
added
920
0
310
40
50
50
2820
3290
4110
3150
2870
1740
19350
0
4970
3690
3810
3640
3880
4230
4110
3430
3110
4050
4190
47220
Water Salt Budget
drainage
salt
1360
1270
1210
1060
670
580
2650
2450
2240
2040
1700
1360
18590
salt storage salt
change
- 820
-5610
-3600
-2700
-1950
-2090
2000*
2000*
2650*
1630*
1630*
- 810
-7670
outflow
3670
3700
2790
2790
3020
3350
4400
4950
5300
4220
5220
4570
47980
*storage change from irrigation, not ground water outflow
-------
Table 36.
Ground water salt flows in Area I, in tons of total dissolved solids,
during the 1971 water year.
Root Zone Salt Budget
Ground Water Salt Budget
MO salt accumulated salt add
depository storage to G.W.
total salt pickup drainage salt storage salt
added salt change outflow
•v]
oo
OCT
NOV
DEC
JAN
FEE
MAR
APR
MAY
JUN
JUL
AUG
SEP
470
0
0
0
0
0
170
510
1320
1690
1440
820
0
0
0
0
0
0
0
0
0
0
0
0
1000
0
0
0
0
0
920
1620
2190
2770
2500
1520
1290
0
0
0
0
0
1070
1890
2550
3240
2940
1830
6000
0
0
0
0
0
4970
5750
5760
5780
6440
6420
1970
1960
1470
1180
690
770
920
1260
1600
1770
2100
2040
1000
-6760
-4400
-3470
-4520
-2550
1540
1540
1240
1140
0
0
4220
4800
2930
2290
3830
1780
3580
4840
5470
61.10
7280
6210
ANN.
6420
0
12520
14810
41120
17730
-15140
53340
-------
Analysis of Results
Examination of the data presented in Tables 29 through 36
indicates some interesting results. An evaluation of the
1971 budgets will be made herein since they reflect the
changes in the system due to the linings, although the
same procedure could easily be applied to the 1969 budget.
The first important consideration is the distribution of the
water from the canal to the drain or subsurface returns to
the river. Based upon the seepage measurements before and
after the linings, a reduction from 840 to 210 acre-feet per
year (75% reduction) canal seepage was determined. On a
valley wide scale, the lining of canals could be expected
to reduce seepage losses from the present 5% to about 1% of
the total canal diversions. The seepage losses from the
lateral system could be expected to be much greater, prob-
ably from 10% to about 2% of the total agricultural diver-
sions. It should be noted at this point that the data tab-
ulated under "spillage" is superfluous, since these flows
were not measured and are included only to make the seepage
losses representative.
The distribution of the water diverted into the lateral
system show that 10% is seepage, 35% is field tailwater
and 55% is actually supplied to the root zone. However,
only 33% of the total lateral diversion is actually used
by the crops, thus making the area farm efficiency equal to
40% if a 7% leaching requirement is imposed.
In the Grand Valley it is useful to examine the ground
water flows and the drainage flows together. Of the
total 9,360 acre-feet entering the ground water basin,
2 490 acre-feet, or 27%, is intercepted and carried away
by the drainage system. Phreatophytes consume about 35% of
these flows, and the remaining 38% returns to the river
through the subsurface aquifer. Thus, of the water carried
by the drainage system (11,500 acre-feet), only 22% is
drainage return flows and 78% is field tailwater.
Even though an examination of the respective water flows
yields useful information for improving water management
practices, the most important considerations to this study
deal with the salinity flow network. From Tables 32 and 36
it can be seen that the total inflowing salt amounted to
22,670 tons (excluding spillage as it is assumed to have no
influence on the budgets), but the total salt outflows
amounted to 78,930 tons, thereby indicating a net gain of
56,260 tons, or 12 tons per acre. This would suggest that
Area I contributes somewhat more per acre than the valley
179
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as a whole and indicates the probability that certain areas
contribute more than others. Thus, a feasible salinity con-
trol alternative must surely consider the delineation of
these areas.
Of the total salt input in Area I, 14,810 tons (0.86 tons/
acre-foot) was computed to be the area contribution to the
ground water system, with 12,520 tons resulting from over-
irrigation (deep percolation), 170 tons from canal seepage,
and 2120 tons from lateral seepage. Thus, for each ton of
salt added to the ground water basin (assuming that all salt
pick up occurs here), 3.8 tons can be expected to result in
the irrigation return flows. The effects of the canal and
lateral linings which reduce water inflows to the subsurface
aquifers by 930 acre-feet annually would reduce the salt
contribution to the Colorado River by 4700 tons.
In terms of extending this conclusion to the valley as a
whole, it is probably premature at this point because
insufficient research has been conducted to quantify the
expected salinity reductions resulting from large scale pro-
jects. For example, if the amount of water reaching the
ground water was decreased by, say, 50%, the question need-
ing study is whether the corresponding salt decrease would
be 50% or, say, only 30%.
180
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SECTION XIII
SALINITY MANAGEMENT ALTERNATIVES
The saline soil conditions associated with inadequate
drainage and the basin-wide urgency of rising salinity con-
centrations make water management in the Grand Valley
increasingly important. The inefficiencies apparent in
present practices of water use result from a combination of
abundant water supply, low water costs, and critical soil
and topographic characteristics. These problems would have
been dealt with more substantially long ago if the economic
penalties had been more severe. In the Grand Valley, the
30% of the acreage highly affected by poor water management
was an insufficient deterrent to offset the belief that use
must be made of all water rights in order to protect them.
Nevertheless, the time has approached when the growing sal-
inity problem in the Colorado River Basin, complicated by
recent and planned development in the Upper Basin States,
has forced areas like the Grand Valley to plan for more
efficient management of water. This study has been the
first attempt to delineate the available alternatives.
Although it has been primarily directed toward the
investigation of the effects of reducing conveyance seep-
age losses, it has provided an insight into the probable
effects of other types of salinity control measures.
The stated objectives of this project could not have been
realized without an extensive evaluation of all the inter-
related factors of the salinity problem. As a result of
this experience, the feasibility of lining canals and lat-
erals to reduce seepage into saline ground water flows
could be determined, but a great deal of supporting gen-
eralized comment is possible concerning the potential of
other management schemes.
During the course of the research effort discussed herein,
the need for further research became quite evident. In
addition, the possibility of certain alternatives seemed
constrained because of either the inadequacy or complete
limitations of water use institutions and legislation.
This discussion can be divided into three parts:
(1) Water management improvements necessary in the exist-
ing system as a prerequisite to reducing_the salinity prob-
lem resulting from irrigation practices in the Grand Valley;
(2) Research needs associated with implementing salinity
control measures; and
181
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(3) Institutional requirements for salinity control in
irrigated agricultural areas.
Water Management Improvements
The Water Quality Act of 1965 amended the Federal Water
Pollution Control Act to require that water quality stand-
ards be established for all interstate waters in the nation
including the Colorado River. The states were given first
opportunity to establish standards, which were then subject
to federal approval. The standards consist of stream class-
ification specifying beneficial water uses to be protected,
water quality criteria which specify limits on various para-
meters, and an implementation plan for necessary pollution
abatement measures to meet established criteria. The Colo-
rado River Basin states jointly developed guidelines for
establishing standards for all interstate streams in the
basin to insure compatibility of standards between states.
An important agreement reached by the states was that no
numerical salinity criteria would be established until such
time that available information on salinity control measures
was adequate to form the basis for establishing equitable,
workable and enforceable salinity standards. The various
states subsequently established water quality standards
which did not include numerical salinity criteria. The
standards received federal approval with the provision
that numerical salinity criteria would be established by the
states as soon as adequate information was developed by res-
earch and technical investigations planned or underway.
The delay in setting salinity criteria has provided the
opportunity for comprehensive study and planning of salinity
control measures, such as this project. The basic salinity
control technology is rapidly being developed so that the
establishment of salinity standards at key points in the
system will be necessary in the relatively near future. The
Grand Valley Water Purification Project, Inc., interested
citizens, and state legislators have realized the need to
promote investigations that will lead to a feasible salinity
control program for the valley. This attitude is extremely
farsighted and will prove beneficial to the irrigators in
the area by studying all available solutions and providing
for increased farm output to offset the costs that will be
incurred. However, the authors feel impelled to state their
opinions concerning the emphasis that should be followed,
based upon the experience gained from participation in this
project. The internal phases of a salinity control program
in the valley involve canal system management, on-farm water
use improvement, and drainage.
182
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Canal System Management
Although the primary use of water is on the farm, the prim-
ary control is not. Therefore/ the first step in effecting
a sound management scheme is the incorporation of more rigid
water company controls. It has been alluded to several
times in the preceding sections that the adjudicated water
supply under normal water years is especially abundant, on
the order of 8-9 acre-feet per irrigated acre. With such a
high water duty, waste and inefficient use are encouraged.
There are several conditions existing that should be improved.
These include the increased control of canal diversions to
reduce spillage into natural washes and drains, company con-
trol of lateral turnouts to avoid the excessive waste below
in the form of dumping water into the drainage system when
not used in multiple use systems, and control on the delivery
mechanism such as a call period to efficiently meet irriga-
tion demands. In summary, for irrigation to continue at the
present or greater levels, while taking into account salinity
control, several new directions must be taken:
(1) Efforts to accomplish as much system (canal and lateral)
rehabilitation as possible, which would imply an extensive
lining program to reduce maintenance and facilitate opera-
tions ;
(2) The first and foremost requirement of efficient water
management anywhere is sound water measurement with accept-
able devices being installed at each lateral turnout and at
major junctions within the lateral system, which requires
that some company control be involved below the turnout; and
(3) An organized and equitable system of call periods
should be implemented to facilitate tighter canal discharge
control .
None of these suggestions could or should be imposed too
rapidly, since such a scheme would constrain to a large
degree an already burdened way of life. However a well
coordinated plan for a gradual transition should be made.
This, of course, means two things. First, a significant
portion of some water rights would be left in the river sub-
ject to abandonment. Consequently, until the social poli-
tical, and economic objectives of the State of Colorado
become clearly defined, it should be required that the right
to use these excesses be left in the Grand Valley. The
area? need is obviously in examining the institutional frame-
work of western water laws to change interpretations so pro-
are maSe for incentives for more efficient water use.
Nuous qestions need to be resolved In ^esub£c£h«JS
before wise and equitable decisions can be made. It should
183
-------
be re-emphasized that the study of feasibility and mechan-
isms of various institutional changes could be effectively
incorporated into the objectives of an extended Grand Valley
Water Purification Project.
The second aspect of management improvements involves the
increasedrequirement of company personnel, equipment, and
operation expenditures which would force an increase in the
price of water to irrigators. External financial sources
such as Federal grants and revenues for renting excess
water would help, but the subtle advantages of expensive
irrigation water as a salinity control technique are many.
Most irrigators would be more reluctant to be wasteful if
farm profits were significantly diminished as more and more
water was not effectively used.
Historical records clearly indicate the potential salinity
control of efficient water management during water short
years. Therefore, it seems well justified to conclude that
although a well coordinated plan of attack between company
management, drainage, and improvements to on-farm water use
is required, the most important and most urgently needed
feature is improvements to canal company operation. Without
detailed consideration of all relevant parameters, a great
deal of resource could be wasted. Thus, there is a great
need to investigate further the legal, social, and engin-
eering factors influencing the optimal method of canal com-
pany management.
On-Farm Water Management
Excessive application of water to soils in the Grand Valley
is undoubtedly the primary cause of salt inputs to the
river system. Increased irrigation efficiencies will be the
most influential factor affecting improvements in salt con-
tribution, drainage problems, and crop production. It is
estimated that the valley-wide farm efficiency ranges bet-
ween 30 to 40%. In this range of operation, every acre-foot
of water consumptively used by crops must be accompanied by
about two and one-half acre-feet that flows as deep percola-
tion or field tailwater. If improved canal management meas-
ures were present, farm efficiency would be sharply enhanced.
The real need in this area is a program to demonstrate
improved irrigation methods and to convince irrigators of
the benefits. Improvement to farm efficiency may be achieved
by the following approaches:
(1) Demonstration that higher water use efficiencies can
result in higher crop production and lower fertilizer costs.
184
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The most effective format is probably similar to this pro-
ject, which could also incorporate some of the research gaps
in present technology, such as the development of prediction
techniques for subsurface return flows, including associated
chemical changes in the moisture movement through the soil
profile.
(2) Incorporation of an irrigation scheduling study into a
demonstration project, where the emphasis includes water
quality. This study could eventually be expanded to a
valley program. This information would aid the irrigator in
determining when and how much water to apply. This_program
has been initiated in other areas, but not as a salinity
control method.
(3) Lateral system rehabilitation must be considered as a
part of any improved farm management scheme because of the
complexity of the present system. Some lateral turnouts
serve over 100 users and thus a real need exists for linings,
division structures, and measurement devices in order to
insure an equitable distribution.
The process of improving on-farm water use will be difficult
to achieve. The need, however, is apparent. With the need
for salinity control being so important, the necessity of a
correlated effort from all factions in the valley is amply
demonstrated.
Drainage
The present open ditch drainage system is largely ineffect-
ive in reducing the high water tables and, for the most
part, is used mainly as a conveyance for field tailwater.
The possibility that these drains actually contribute to
the ground water in the test area was found non-existent,
but they may at other localities throughout the valley. In
any event? the reason for the general inadequacy of these
drains is based on the fact that insufficient attention
aroears to have been given to the true characteristics of
the problem. Piezometric readings and stratum surveys taken
throShout the valley indicate that a relatively impermeable
Into and out of the cobble, thus increasing the Drainage
185
-------
pickup throughout the valley, is not known, the type and
extent of drainage may be very important to future salinity
control proposals.
It can be realized that area drainage should be a combination
of interceptor drains to collect ground water flows from
higher lands, pump drainage to relieve vertical gradients and
lower water tables in selected areas, and field tile-type
drainage to control the fluctuations of the moisture levels
in the root zone. These are known to be important principles
in successful farming operations. Because the expense of
field drainage is high and the bulk of the costs probably
fall on the land owner, further effort is needed to find an
acceptable drainage technique.
An improved drainage system without an accompanying increase
in on-farm water use efficiency and improved operation of
canals would only magnify the already critical problem.
Obviously, if the water tables are lowered, more water can
and will be applied, irrigated acreages will increase into
the reclaimed areas, and salt loadings would probably rise.
However, if effective drainage accompanies improved water
management practices in general, the productivity of local
agriculture will be greatly increased as the salt problem
is alleviated.
Future Research Requirements
There are two basic requirements for further research in
the Grand Valley. The first is concerned with further
technological development. The second is related to dem-
onstrating to local irrigation officials and irrigators both
the importance and feasibility of alternate salinity control
methods.
Needed Research in Filling Existing Technological Gaps
The empirical nature of certain assumptions made as part of
this modeling effort has been pointed out. First, the dis-
tribution of the salt actually contributed from the soil and
aquifer is not known. If, for example, most of the salts are
added in the ground water flows, then field drainage which
intercepts the deep percolation losses before they come in
contact with these deeper strata becomes an effective salin-
ity control technique. In addition, it is not unreasonable
to assume that different areas with their different soil
characteristics, cropping patterns, and water-use practices
yield different salt loads. Thus, one of the most pressing
186
-------
technological needs is the development of prediction tech-
niques for describing the quantity and quality aspects of
subsurface return flows. Models of this type should incor-
porate sufficient sophistication to predict ionic exchange
and other characteristics of water and salt flows in soils.
The necessity of models of this format is amply demonstrated
by the need to predict in acceptable detail the effects of
various salinity control programs.
Because any salinity control practice would hopefully improve
the local agricultural conditions, the knowledge of the basic
parameters surrounding irrigation scheduling should be inves-
tigated. For example, it is known that certain growth per-
iods during the season are critical to optimizing production.
Research should be conducted to test the correlated effects
of water application, soil salt concentrations, and the rela-
tive preponderance of the various cations on crop yields.
Specifically, the salinity control aspects of irrigation
scheduling should be given attention, since this point of
view has not been taken previously.
Need for Demonstrative Research
The success of water quality improvement programs without
extensive public and private support has always been highly
questionable. Salinity management in the Grand Valley will
be no exception. There are at least two major needs remain-
ing for demonstration in the Grand Valley. They are improved
on-farm water management through irrigation scheduling and
field drainage. Actually, field drainage would probably be
best suited if the largest proportion of salts were being
picked up below the root zone. Individual demonstration pro-
jects similar to this particular one serve to evaluate some
of the gaps in basic knowledge and to solicit local cooper-
ation. Much of the important basic research should be accom-
plished before actual regional salinity management is under-
taken on a large scale, in order to facilitate a careful
planning schedule. Consequently, demonstration projects
planned for the future should involve some coordination
among all three types of programs in order to demonstrate
successfully the absolute requirement for coordination bet-
ween salinity control programs. It should be noted once
again that implementation of salinity management methods,
without considerable planning based on sound experimental
evidence and local conviction, may be very ineffective in
the long run.
187
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Institutional Requirements for Salinity Control
When all aspects are considered, the institutional constraints
compromising the wishes of local water users and regional
salinity planners will be the most difficult and the most
important to resolve. Salinity control in the Grand Valley
simplifies immediately to the restricted use of water result-
ing in a quantity that need not be diverted. The question
immediately confronted is what happens and who obtains the
water saved by salinity control programs in the Grand Valley.
The legal constraint here is the possibility of forced abandon-
ment of some of the decreed water right in the valley and then
the successive reapportionment to other uses. Thus, the
water use must be changed from irrigation to another desired
use if it is to be left in the valley supply.
Ineffective drainage, excessive salt inputs to the Colorado
River, and marginal agricultural production from at least
30% of the valley are not three independent problems, just
one - poor water management practices by an irrigated agri-
culture. Grand Valley is not unique in this respect either.
Consequently, a step parallel to conducting research on
feasible solutions is the implementation of salinity control
measures, which will require the formation of an administra-
tive body to coordinate the activities of the various entities
concerned with irrigation in the valley. These and similar
questions lead the writers to suggest a valley authority for
coordinating the salinity control program. The basic struc-
ture of this institution would allow it to seek salinity
control funding, research funding, etc., and to transmit
pertinent data and planning efforts between the federal-
state entities and the local organizations. It would also
stimulate the interest and investigation of economic, social,
and legal problems influential in salinity reductions.
Miller's (21) conclusion that the scope and severity of the
drainage problem in 1916 required a complete community organ-
ization dedicated to the problem led to the formation of the
Grand Junction Drainage District. The prospect of obtaining
federal money for canal and lateral lining as a first step
in salinity control in the late 1960's led to the organiza-
tion of the Grand Valley Water Purification Project, Inc.
The next step is a logical extension of the GVWPP into a
regional salinity management coordinating council. Since
the present organization of GVWPP is comprised of local
irrigation and drainage officials, it seems justified to
broaden the format to include such responsibilities.
188
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The possibility of organizational consolidation at the local
level among the existing irrigation companies to facilitate
more efficient irrigation operations as well as to operate
the valley salinity control program should also be considered.
Such a consolidation would allow a pooling of personnel,
equipment, and finances, thereby providing some savings in
operational costs, but more importantly, allowing the entire
Grand Valley irrigation enterprise to be operated as a truly
integrated system.
189
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SECTION XIV
ACKNOWLEDGMENTS
The authors have become indebted to many individuals
during the course of this study. Especially rewarding have
been the associations with Mr. George Bargsten, Mrs. Barbara
Mancuso, Mr. Ted Hall, Mr. Jim Taylor, and Mr. Orlando Howe
for their tireless efforts to conduct this research success-
fully in the Grand Valley.
Others who have contributed greatly to the results of this
work on different occasions include Miss Diane Peterson,
Mr. Robert Evans, Mr. Thomas Huntzinger, Mr. Van Steven
Higinbotham, Mr. Ray Bennett, and Mr. Hugh Barrett, most of
whom have also been students of the senior author.
The cooperation extended on numerous occasions by the offi-
cials of the Grand Valley Water Purification Project, Inc.,
has been greatly appreciated throughout the period of study.
The writers would also like to thank Miss Kevin Feigen for
typing the final drafts of this manuscript.
The work from which this report is derived was supported by
funds provided by the U.S. Environmental Protection Agency,
Water Quality Office, Demonstration Project 13030 DOA.
Especially appreciated has been the support of the Project
Officers, Mr. L. Russell Freeman (FY69), Mr. James R. Vincent
(FY70-71), and Dr. James P. Law, Jr., since July 1, 1971. In
addition, the constructive criticisms offered by Mr. C. E.
Veirs of EPA throughout the course of this investigation have
been very helpful.
Gaylord V. Skogerboe
Wynn R. Walker
191
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SECTION XV
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39. Walker, W. R. , and G. V. Skogerboe. 1971. Agricultural
land use in the Grand Valley. Agricultural Engin-
eering Department, College of Engineering, Colo-
rado State University, Fort Collins, Colorado.
July. 75 p.
197
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SECTION XVI
PUBLICATIONS
1. Walker, Wynn R. 1970. Hydro-salinity model of the
Grand Valley. M.S. Thesis, Colorado State Univer-
sity. August.
2. Skogerboe, Gaylord V., and Walker, Wynn R. 1970.
Salinity management in the Upper Colorado River
Basin. Paper 70-722, Presented at Annual Winter
Meeting, ASAE, Chicago, Illinois. December.
3. Skogerboe, Gaylord V., and Walker, Wynn R. 1971. Pre-
construction evaluation of the Grand Valley Salin-
ity Control Demonstration Project. Report AER70-71
GVS-WRW5, Agricultural Engineering Department,
College of Engineering, Colorado State University,
Fort Collins, Colorado. June.
4. Walker, Wynn R., and Skogerboe, Gaylord V. 1971. Agri-
cultural land use in the Grand Valley. Report
AE71-746 WRW-GVS1, Agricultural Engineering Depart-
ment, College of Engineering, Colorado State Univ-
ersity, Fort Collins, Colorado. July.
5. Skogerboe, Gaylord V., and Walker, Wynn R. 1971. Salin-
ity control research in Grand Valley. Paper pre-
sented at the Twenty-Eighth Annual Meeting of the
Colorado River Water Users Association, Las Vegas,
Nevada. December.
199
U.S. GOVERNMENT PRINTING OFFICE:197Z 514-148.• 69 1-3 ^. J J
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
i 1. Report No.
4. Title EVALUATION OF CANAL LINING FOR SALINITY
CONTROL IN GRAND VALLEY,
5. J> jporf Z/
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