IRRIGATION
FIELD DAYS
REPORT
1976
A Report
of CSU's
Salinity Research
in Grand Valley
Sponsored by
the EPA.
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y,Z:' I/&
Kg
IRRIGATION
FIELD DAYS
REPORT
1976
A Report
of CSU's
Salinity Research
in Grand Valley
Sponsored by
the EPA.
Prepared by
Agricultural Engineering Department
Colorado State University
Fort Collins, Colorado 80523
With contributions from
Robert G. Evans
Stephen W. Smith
Wynn R. Walker
Gaylord V. Skogerboe
In association with
James P. Law, Jr. ^
Chief of Irrigated Agriculture Section
Robert S. Kerr Environmental Research Laboratory
Environmental Protection Agency
Ada, Oklahoma 74820
August, 1976
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Acknowledgements without the support and work from certain
individuals and groups of individuals the
Irrigation Field Days and this report would
not have been possible. Special thanks to
the cooperators on the various laterals for
their patience and support during the past
three years, to the local irrigation companies
for their continued support during the past 8
years, and the Grand Junction Drainage District
for their participation in the construction of
improvements. We are grateful to the CSU
Cooperative Extension Service for their time
and contributions to the Irrigation Field
Days. The assitance of Mr. Richard L. Aust
in preparing this report and Mrs. Debby Wilson
for typing the manuscript is very much appre-
ciated.
In addition, the data collection, field
serveying, mapping, and construction phases
of the project could never have been accom-
plished without the labor input of numerous
summer employees and staff members. In
particular, the long-term efforts of Mr.
George Bargsten in handling field operations
and Mrs. Barbara Mancuso in supervising
laboratory operations have been instrumental
in accomplishing the goals Of this research
program.
No endorsement of products used during the
course of this project is intended nor is
criticism implied of products not used.
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3
Irrigation
and
Salinity
In much of the western United States, a farmer
must rely on irrigation to supplement an other-
wise meager supply of rainfall in order to
provide for the moisture needs of his croplands.
In fact, about 85% of all water diversions in
the West are intended for irrigation purposes.
Irrigation water contains various dissolved
minerals like sodium and calcium that have
important consequences in agriculture. These
minerals, collectively called salinity, are all
too familiar to most irrigators since salts
that are not continuously leached from the soil
will build-up in the soil and render even good
soils totally unproductive (Fig. 1). However,
many farmers may not be familiar with salinity
in a larger context, i.e., the downstream conse-
quences of salinity derived from the irrigation
of their lands.
The interrelationships between irrigation and
salinity are complex and are therefore very
often misunderstood. When an irrigator applies
water to a field an average of about one-half is
extracted by the crops and transpired to the
atmosphere as part of plant growth and develop-
ment processes. Salts in the applied water are
left behind in the soil to be leached by the
remaining flow. Thus, as these drainage waters
find their way back to streams via groundwater
movement, their salinity concentrations are
significantly higher. As these flows mix and
proceed downstream, the overall quality of the
flow is also poorer.
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4
There is another dimension of irrigation and
salinity that merits attention. Waters passing
through soil and aquifer materials generally
dissolve salts in these materials and thereby
contribute even more salts to the receiving
waters than originally carried by the irrigation
diversions. In some areas, the volume of soluble
salts is very large and even the most efficient
irrigators have a pronounced impact of down-
stream salinities.
Salinity generally is of little consequence
when the supply of water is much greater than
the demand. However, as more and more of the
available water is committed to development,
salinity may become the most important factor in
the beneficial use of the water. The Colorado
River Basin (Fig. 2) in the southwestern U.S.
is one of the most graphic illustrations of the
developmental encroachment of salinity. And,
the Grand Valley as a setting for the Irrigation
Field Days is probably most appropriate because
the valley is one of the most significant con-
tributors to the basin-wide salinity problem,
and as a consequence, was among the first to
receive research funding and considerable focus
upon implementation of appropriate technological
solutions.
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5
Figure I. Example of the effects of salinity
buildup in soils.
Figure 2. Colorado River Basin.
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6
and the Valley
Th© Basin Although modification of the Colorado River flow
has been beneficial for flood control, irrigation,
recreation, municipal and industrial water supply,
and hydro-electric power, it has nevertheless
resulted in doubling the salinity concentration
in the Lower Basin. Today it is estimated that
for every part per million increase in salinity,
approximately $200,000 in related damages will
occur, primarily to the users in Arizona, Cali-
fornia, and the Republic of Mexico.
A large share of the annual river flow allocated
to the Upper Basin states of Colorado, Utah,
Wyoming, and New Mexico, is yet to be developed.
To do so will cause further salinity problems
downstream (up to as much as $60 million annually
by the turn of the century). Solving this problem
will require a concerted mutual effort to reduce the
impact of existing salinity sources and those
anticipated as part of new water uses in order to
offset the effects of further water development.
For instance, the possibility of coal and oil
shale developments, along with the continued
requirements for irrigation and urban demands,
will necessitate the removal of about 2 million
tons of salt annually at full development.
Initial studies have shown that among the most
economical means of reducing some of the river's
salt load is to improve water management practices
in the irrigated areas. This in more simple terms
means that canals, laterals, and ditches need to
be lined; over-irrigation needs to be minimized
by better on-farm irrigation practices; irrigation
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7
systems need to be designed and constructed that
are better suited to local climatic, soil, and
crop conditions; and incorporation of new
technological aids such as irrigation scheduling.
However, in the context of irrigated agriculture,
two important problems still remain; (1) What
irrigated areas should receive attention first?;
and (2) In these areas, what is the best program
for both reducing salinity and increasing
agricultural productivity?
The answers to these questions are not self-
evident nor are they easily found. At the same
time, the difference between the right and wrong
solutions in a single irrigated area can easily
amount to several million dollars per year.
Consequently, a large research effort has been
undertaken to search out the answers to these
questions.
The Agricultural Engineering Department at
Colorado State University, with funding support
and program direction from the Environmental
Protection Agency, has been a leader in the invest-
igation of alternative salinity control measures.
Since 1968, the Grand Valley (Fig. 3) has been
the setting of these research and demonstration
efforts and it may be interesting to review the
results.
Early explorers and trappers concluded that the
Grand Valley was a poor risk for agriculturally
related activities, a concept easily understood
when the areas outside the irrigated lands are
viewed. But the first pioneering farmers
rapidly disproved this notion with the aid of
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8
Figure 3. Map of the Grand Valley showing the
location of the project area.
irrigation waters diverted from the Colorado
and Gunnison Rivers. Through a long and tedious
struggle against natural and man-made obstacles,
todays irrigation system evolved to supplement
a small supply of precipitation during the
190-day growing season. Farmers use furrow
irrigation (Fig. 4) primarily to apply water to
their fields because it offers advantages of
both low cost and water control on lands generally
having slopes of 0.5 to 1%. An illustrative
summary of today's land use patterns in the valley
is shown in Fig. 5.
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9
Figure 4. Furrow irrigation of corn.
120
100
80
60
40
20
Sugar Beets
Orchards
Grain
Idle
Posture
Corn
Alfalfa
"Miscellaneous
Industrial
Municipal
Phreatophytes
Borren
Soil
Open Water
Municipal -
industrial
Phreatophytes
and
Barren Soil
Irrigable
Croplands
Irrigable
Croplands
Municipol-
Industrial
Open Water
Surfaces
Phreatophytes
and
Borren Soil
Total
Figure 5. Land use patterns in the Grand Valley.
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10
The futility of irrigation without adequate
drainage was quickly demonstrated in the valley
as low-lying acreage became waterlogged. Salinity
manifested itself quickly too as the farmers
determined that soils were high in gypsum and lime
salts. A look at a typical geologic cross-section
of the valley shown in Fig. 6 reveals that most
of the local soils are derived from the Mancos
shale formation. Mancos shale was created
during a period when the area was under great
inland seas and naturally contains large volumes
of crystalline salt in its layered structure.
Thus, the soils resulting from weathering of the
shale also contain these salts, which force
irrigators to give special attention to their
irrigation practices.
With the high salinity content of soils and
aquifers in the valley and an abundent water
supply, large quantities of salts are leached
by seepage and over-irrigation from the valley
and ultimately into the Colorado River.
UNCOMPAHGRE UPLIFT
r-'; ,}~^i
, ^GRANITE , GNEISS ~
AMPH.BOLITC.CTC j> V
V * (UNCONFORMITY h •"*
GRAND MESA
.AVA 500- CEN0Z01C
"W^ioct tertiary
/-WASATgH~65Q' (EOCENC)
^Tj-AfEAU valTeyT (PAlEOCENE)
-
(PRE •
\ CAMBRIAN)
Figure 6. Geologic cross section of the Grand
Valley.
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11
Early investigations in the Colorado River Basin
identified the Grand Valley with a contribution
of 700,000 tons of salt annually as the most
important irrigated valley in the Upper.Basin.
In 1967, local irrigation companies formed
a cooperative organization called the "Grand
Valley Water Purification Project, Inc." and
petitioned the Federal Water Quality Administra-
tion (later to become part of the new Environ-
mental Protection Agency) for funds to line
their canals and ditches. Funds were provided for
up to 70% of the lining costs of the canals,
laterals and ditches in the 4,600-acre test
area about two miles east of Grand Junction.
As part of the project and with the available
funds, the Agricultural Engineering Department
at Colorado State University undertook the
technical evaluation of the project. More than
eight miles of canals and ditches along with
about five miles of laterals were lined with
concrete and shotcrete linings. The results
of the CSU investigation indicated that approx-
imately 4,700 tons of salt annually were
eliminated from the river by these linings.
It became apparent during the canal lining study
that the major contributions to the valley
salinity problem were not the large canals and
ditches but the smaller lateral networks and
the over-irrigation of fields themselves. In
fact, canal and ditch seepage probably contribute
no more than 15% of the total salts now entering
the river system as opposed to 35% from lateral
seepage and 50% from cropland irrigation. As
a result, two additional investigations were
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12
launched in the demonstration area. The first
involved scientific irrigation scheduling, a
process in which soil moisture and climatological
data are integrated by a computer analysis to
advise an irrigator when to irrigate and how much
water to apply. Data from this study indicated
that irrigation scheduling would have a small
effect on improving on-farm water management
because the existing irrigation systems did not
allow irrigators to evaluate how much water
they were applying. The scheduling could be
expected, however, to be more effective if farmer
confidence could be gained and certain structural
improvements such as flow measurement devices
were constructed. The second investigation centered
on the feasibility of field drainage as a salinity
control alternative. Waters percolating below
the crop root zone can be intercepted by the field
drainage pipes before the salts in the lower
subsoils and aquifers can be dissolved. One field
drainage system was built as part of this project
and was successful in intercepting the flow as
intended.
The canal lining, irrigation scheduling, and
drainage studies were evaluated individually. In
order to extend these research results to the
formulation of comprehensive plans for salinity
control on a valley-wide scale, it is necessary
to evaluate the interrelationships which exist
among the alternatives. To do this, a two phase
effort was initiated in 1973. The first phase
involves a highly refined research investigation
into the physical and chemical processes of salt
pickup from local soils. The second phase was a
large demonstration of the combined effects of
irrigation improvements.
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13
Research
Programs
One of the most effective methods of education is
through demonstration, particulary with farmers
who must operate on a very narrow margin of
profit and with high levels of capital investi-
ment. In our present age of technology, volumes
of new ideas are being presented to the farmer
each year from which he must decide which ones
will be beneficial to his operation. Since one
or two years of low production can be disastrous
if a new idea isn't feasible, the surest way for
the farmer to judge the merits of a new idea is
to be able to evaluate its performance in his
own area. And, it should be noted that efforts
to deal with salinity originating from irrigated
agriculture will be futile without first obtaining
the support of irrigators.
The damage caused by increased salinity in the
area is quite apparent and is recognized by most
local people. The point requiring proof is that
the situation can be improved by better water
management procedures and, even more important,
that the program is economically feasibile.
The economic analysis of improved water management
is more complicated than just water savings
versus labor costs. First, since excess water
passing through the root zone also removes the
nutrients required for plant growth, the cost of
the additional fertilizer and the labor for
application must be considered. Second, when too
much water is applied, the soil may become water-
logged for periods of time during the growing
season causing some of the plant roots to die,
which will affect plant growth and reduce
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14
yields. Third, with the low permeability of the
soils in the Grand Valley area, applying large
quantities of water necessitates running water
accross the field for long periods of time,
resulting in large quantities of tailwater run-
off. These factors directly affect the farmer
applying the water. To this must be added the
cost of higher water tables and higher soil
salinity levels on neighboring farms, along with
higher salt content of the river water for down-
stream users. This project will show the bene-
fits of improved water management on a local
scale, as well as providing necessary information
for calculating the salinity effects to downstream
users resulting from various water management
practices.
Another major purpose of the detailed investi-
gation is to develop equations which will
permit the calculation of salinity reduction per
unit reduction of subsurface return flow. At the
present time, data are available from the studies
noted earlier showing the contributions to salt
pickup from canal and lateral seepage, as well as
on-farm deep percolation losses. However, the only
method for predicting the reduction in salts
entering the river through implementation of any
salinity control measure(s) is by assuming a one-
to-one relationship between water and salt. That
is, if the subsurface return flow is reduced by
50%, the salt is also reduced by 50%. It is impor-
tant for the overall salinity control planning that
this relationship be verified. The objectives
of the project are also to supply economic
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15
functions for levels of crop production based
on fertility level and amount of irrigation.
From these production functions, the optimum
utilization of fertilizer and water can be
developed, taking into account salinity control
goals.
The site requirements for this phase of the
research were quite restrictive. An area of
approximately 20 to 25 acres was required for
a system of intensly instrumented plots where
conditions could be sufficiently isolated to
allow the evaluation of differing irrigation and
fertilization practices. The field needed to
be located in an area such that all subsurface
flows crossing the area could be intercepted
and removed. A smooth, fairly level topography
over the farm land with slopes not exceeding 1%
was necessary for the successful use of furrow
irrigation. However, a drainage channel, either
natural or man made, should be nearby with
sufficient depth to allow the water removed by
the subsurface drains to leave the area under
gravity flow. For construction purposes, a
continuous layer of shale underlying the area
at a depth of between six and twelve feet was
required. The slope of shale, if possible,
should not exceed the slope of the ground
surface.
The site selected for the intensive study area
was 23 acres of land owned by Mr. Kenneth
Matchett. The farm, located north of the city
of Grand Junction, is bounded on the north by the
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16
Government Highline Canal and on the east by a
natural waste channel known as Indian Wash
(Fig. 7). The wash averages approximately
25 feet in depth and is cut into the shale,
thereby effectively intercepting subsurface flows
originating in the lands above and seepage from
the Government Highline Canal. Water is supplied
to the area by a lateral which diverts from a
canal operated by the Grand Valley Water Users
Association.
Figure 7. Location of the Matohett farm
project area.
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The depth of shale over the fields ranges mostly
between six and twelve feet, witji isolated areas
as shallow as 1.3 feet and as deep as 21 feet.
While the deep areas were not used for the plot
studies, the shallow areas were ideally suited
for a special study to evaluate the effects of
long contact periods of water with shale on the
chemical water quality of subsurface irrigation
return flows. The plane of the shale as a whole
slopes to the southwest with some undulation.
However, it was possible to construct the system
with all of the perforated drain lines lying on
top of the shale and only a minimum of excavation
into the shale for the main outlet lines.
The study area was divided into 54 plots which are
100 feet by 100 feet in size; five plots are 40
feet wide by 500 feet long; two plots are 40 feet
wide by 300 feet long; and two plots are 40
feet wide by 200 feet long. Thus, a total of
63 plots have been constructed. Each plot was
constructed to operate as a large lysimeter or
a tank with previse measurements of all water
and salt flows. A trench was excavated slightly
into the shale along the lines dividing the plots
and then a plastic curtain was placed vertically
in the center of the trench to divide the
individual plots. The upper edge of the curtain
ended approximately three feet below the surface
to avoid interferance with farming operations
and then "sealed" to the shale by backfilling
to the original elevation of the shale with
compacted clay. A drainline encased in a gravel
filter material was located around the periphery
of each plot inside the curtain (Fig. 8).
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18
Figure 8. Installation of plastic curtain around plots.
Upon leaving the plot area, the water is trans-
ported via solid pipeline to a measuring station
where quantity and quality can be monitored
Each plot is used for a different replication of
the crop, fertilizer and irrigation treatments.
The crops being grown are corn, grass, alfalfa,
and barley since these are the main field crops
grown commercially in the valley. By varying
irrigation timing and amounts, crops, and nitro-
gen fertilizer levels on the different plots
while monitoring quality and quantity of both
inflow and outflow waters, the effects of these
parameters on return flow salinity and crop
yields is evaluated.
With the shale floor and plastic membrane walls
creating a box around each plot, the plot will
operate as a large lysimeter. A salt and water
budget will be developed for each plot and compared
to those developed for the other plots. From
these data, equations can be developed to predict
the variation in salt load entering the river
caused by variations in agricultural practices.
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Economically feasible means of controlling the
salinity associated with irrigation return flows
have been evaluated individually and independently
in several earlier investigations. Extension
of these results to comprehensive plans tor
controlling salinity on a large scale requires
the description of interrelationships which
exist among the alternatives. Thus, an impor-
tant step in solving salinity problems is to
investigate the nature of improvements incor-
porating several alternatives, or in simpler
terms, assessing the impact of a "package of
salinity control measures". Salinity can not be
totally eliminated in agricultural areas without
special measures such as desalination, but
salinity can be minimized by implementing an
optimal package of control measures.
The costs of salinity control to sufficiently
compensate for future water resource developments
in a region like the Colorado River Basin will be
high. Savings achieved through the implementa-
tion of the most cost-effective alternatives can
therefore be substantial. The practical phase
of this research was designed to develop and
demonstrate cost-effectiveness relationships for
salinity control in the Grand Valley of western
Colorado. The principles derived by this project,
however, should be helpful in application else-
where .
The primary objective of this demonstration
project is to show the adventages of implementing
a range of improvements within the lateral
subsystems. The lateral subsystem begins at the
Lateral
Improvements
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20
canal turnout and includes all of the water
conveyance channels below the turnout and the
farm lands served by the lateral water supply.
These improvements included those evaluated in
earlier studies such as construction of improved
irrigation systems and improved water management
techniques like irrigation scheduling and water
rotation.
This phase of the project began when an announce-
ment and a location figure of the demonstration
area was published in the local newspaper (Fig. 9)
$230,000 EPA grant to fund
new seepage control project
Funding has been received from the
U.S. Environmental Protection
Agency to construct irrigation im-
provements in the area between Grand
Junction and Clifton, according to the
Agricultural Engineering Dept. at
Colorado State University.
The area is the same that received
funding five years ago for concrete and
gunnite lining of canals and laterals to
reduce seepage.
CSU officials said the advantage in
continuing work in the area is that
much is already known about the
underground water and the salt
flowing into the Colorado River from
the area. Additionally, they said,
considerable money has been spent on
both equipment and personnel for
instrumenting the particular
demonstration area.
Hie amount of information provides
a strong basis for evaluating the ef-
fectiveness of irrigation im-
provements in reducing river salinity.
The study area was originally
selected because it is fairly
representative of the Grand Valley.
Five canals traverse the area, thereby
allowing greater participation by the
majority of irrigation entities in the
valley.
The EPA has granted $230,000 for the
lining of laterals, construction of new
on-farm irrigation systems, and in-
stallation of tile drainage.
The funds can be used to pay 70 per
cent of the construction costs, with the
farmer paying the remaining 30 per
cent.
The demonstration project will use
two laterals under each of the five
canals in the study area. Laterals will
be selected to represent a wide variety
of conditions.
To participate, all oX the irrigators
under a lateral must be willing to
share in the costs of lateral lining and
on-farm irrigation improvements. A
few of the laterals have Already been
extensively lined with concrete under
the previous demonstration project
CSU officials said the selection of a
lateral and all the crop land served by
a lateral, rather than an individual
farm, has a tremendous advantage in
allowing control at the lateral turnout.
Thus both the quantity of flow and .the
time of water delivery can be con-
trolled, thereby providing improved
water management and higher crop
yields.
The new construction program will
be explained by CSU personnel at the
Holiday inn from 9 a.m. to 4:30 p.m.
Feb. 27. Any irrigator having lands in
the study area can inquire at that time
about possibilities for participating.
The new study will use a variety of
irrigation methods, including "tuning
up" methods presently in use. CSU
said considerable experience has been
gained in improving the existing
irrigation methods while evaluating
irrigation scheduling as a salinity
control measure in the Grand Valley.
However, more advanced irrigation
methods have not been evaluated in
the Grand Valley for salinity benefits.
Irrigation systems to be constructed
under the new project include
automated farm head ditches, border
irrigation, sprinkler irrigation, and
trickle irrigation. Tile drainage also
will be constructed on some farms.
In particular, some of the lands near
the Colorado River will require
drainage facilities to reclaim them for
high level productivity.
CSU officials said the most
significant aspect of the project is use
of a salinity control "package"' rather
than a single control measure.
Field days will be conducted in the
third year — 1976 — of the project,
probably during August.
Figure 9. Newspaper article advertizing project.
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21
The article stated the funding available, its
purpose and conditions for qualifying, and the
availability of project representatives at
an open-house on February 27, 1974 at the
local Holiday Inn to answer further questions.
The project was funded by the Environmental
Protection Agency and Colorado State University.
The project paid 70% of the total cost of the
improvements and the participants contributed
the remaining 30%. The 30% matching money could
be paid in cash or contributed by either the
irrigators or another local agency (such as
the Grand Junction Drainage District) through
labor. In the case of pipelines, The irrigators
could install the pipe to meet the 30% matching
requirements. All field drainage was matched
by the work of the Grand Junction Drainage
District. In some cases the local contributions
exceeded the 30% matching requirement but could
not be reimbursed since the terms of the grant
only stipulated a minimum matching requirement.
Prior to the open-house, the writers envisioned
a long period of door-to-door field contact.
However, the response to the newspaper article
was such that at least forty individuals repre-
senting fifteen laterals responded (only ten of
which were actually in the demonstration area)
and the field contact was not necessary. At
the completion of this project, the time saved
by this open house and the over-whelming
response will undoubtedly rank as one of the
single most important events leading to the
project's success.
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At the open-house, each inquirer was advised that
the best action at the time would be to contact
others on the lateral, briefly explain the project
objectives, and enlist support. On March 18,
1974, contact with the individuals who came to
the open-house was re-established and meetings
were scheduled over the next two weeks. With
the exception of two cases, the meetings were
unqualified successes in gaining the acceptance
of the people involved. Lateral groups accepting
the project were told final site selection would
not be made until the fall or winter so that each
lateral would be evaluated for its usefulness to
the project objectives and to allow time for the
people to finalize their willingness to be
included.
The laterals eventually selected were evaluated
on the basis of four broad criterion:
(1) In a lateral system, 100% participation
must be obtained from all the water
users on presently irrigated lands
(larger than 1 acre) served by this
lateral;
(2) The degree of anticipated participation
in all of the three phases of the
project: pre-evaluation, construction,
and post-evaluation covering the antic-
ipated three-year period of the project;
(3) The type and extent of problems represented
and the different solutions and alterna-
tives which were agreeable to the land-
owners ; and
(4) The analysis of the least cost expendi-
tures .
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23
The laterals were also selected to include as
many canals as possible. The final selection
as illustrated in Fig, 10 and Table 1 had two
laterals under the Highline Canal, one under
the Price Ditch, three under the Grand Valley
Canal, and three under the Mesa County Ditch.
It should be pointed out that the lands served
by the Highline Canal in the Demonstration area
came under a carriage contract with the Palisade
Irrigation District (Stub Ditch) and the Mesa
County Irrigation Company (Price Ditch). There-
fore, all the irrigation entities in the demon-
stration area are involved directly in the project.
Scole I Mile
Water Supply
Land Under Study Lateral
Hydrologlc Boundary
Canal or Ditch
Drain or Wash
Grand Valley Canal
Stub Ditch
Government
j Highline
/ Canal
/ Price Ditch
|
N
Figure 10. Location of the nine selected lateral systems to be
incorporated in the project.
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24
Table 1. Final selection of laterals to be included in project.
Lateral
No.
Canal
Identifi- No. of
cation Acreage Irrigators
1. Highline Canal
2. Highline Canal
3. Price Ditch
4. Grand Valley Canal
5. Grand Valley Canal
6. Grand Valley Canal
7. Mesa County Ditch
8. Mesa County Ditch
9. Mesa County Ditch
TOTAL
HL
C
32.4
1
HL
E-/
88.6
2
PD
1771/ 4/
68.8
6
GV
92
59.9
6
GV
95-Z
195.7
13
GV
160
194.3
8
MC
3
6.3
1
MC
io-/
133.4
9
MC
30-/
34.7
1
816.8
47
1/ These laterals were part of the earlier EPA funded canal and
lateral lining study.
2/ This lateral was part of the earlier EPA funded field drainage
study.
3/ This lateral is a partial consolidation of lands from
three different laterals. ( 60 acres).
4/ A portion of this lateral was included in the previous EPA
funded irrigation scheduling program.
NOTE:
An irrigator is difined as a person who farms more
than one acre. In actuality 89 persons are involved
in the operation of this project.
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25
Once the laterals were identified by their
special problems, alternative solutions were
proposed to the landowners and a course of
action was developed in complete assordance
with the wishes of all parties. Then, project
personnel analyzed the costs of the various
forms of the alternatives and prepared basic
quantity take-offs and preliminary cost estimates.
Further meetings were held and a final action
plan was mutually adopted. Any other individual
materials necessary for the preparation of the
final bid documents to comply with the land-
owners wishes were then collected.
Because the respective improvements needed to
be compatible with the objectives of the project,
an overall design philosophy was formulated
to govern the general designs of the laterals.
The first major consideration was the placement
of flow measurement devices in the system. It
was determined all measurements of lateral
discharge were necessary immediately below the
lateral headgate and at all divisions to farm
delivery points on the main ditch so the farmer
would know how much water he had by the difference
between his and his neighbors flow reading. To
simplify use, all measurement devices were
designed to indicate flow rate directly without
the use of tables or any calculations (Fig. 11).
Another consideration was that all pipeline and
concrete ditch slbpes would be governed by the
general slope of the land surfaces where possible.
This reduced the costs by eliminating drop
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26
structures and energy dissipation facilities.
An attempt would be made to consolidate as much
land and as many laterals as possible into
one lateral to minimize the unnecessary dupli-
cation of facilities.
Whenever a lateral passed by or went through a
subdivision or other urban type area, an attempt
was made to convey the water in a closed
conduit. This was done primarily for health
and safety reasons as well as for the aesthetics
of eliminating an open ditch. In addition,
there were fewer problems with trash and debris.
Under roadways and access routes, the PVC plastic
irrigation pipes were encased with concrete
pipe. Corrugated metal pipe (CMP) culverts
needing replacement or relocation were replaced
with a high sulfate resistant concrete pipe.
The concrete pipe was about one half the material
cost of CMP, but the initial installation costs
were higher. However, in the saline soil condi-
tions of the Grand Valley, the concrete could be
expected to outlast the CMP by at least 20 years.
,00° «
Figure 11. Upstream end of a Cutthroat flume shewing
staff gauge which may be read in Colorado
miner 's inches or cubic feet per second.
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27
The first step in the collection of design and
pre-evaluation information was to have project
personnel talk to the farmers and to walk the
individual laterals with aerial photos while
obtaining the following information: individual
field crops; crop specing; planting dates;
irrigation methods; all places where tailwater
enters the system; all places tailwater leaves the
system and whether it is reused or is lost; and
the identification of all potential problem areas
such as culverts, division boxes, deep
erosion area requiring fill, trees, fences,
location of buried utilities, location of any
existing flow measurement structures, etc.
Project personnel then surveyed all the preselected
laterals to determine pertinent information
including the slopes and lengths of various
reaches, cross-sections and profiles of the
laterals, field sizes, field slopes, and in some
cases the topography of the individual fields
(Fig. 12). After evaluating the local topography
and location of existing structures. The hydraulic
computations necessary to insure proper performance
of the individual components were undertaken.
Figure 12. Project pevsonel surveying lands.
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28
After designs were completed and approved by
the individual irrigator or lateral groups, the
construction was initiated in the fall of 1974,
continued through the spring of 1975 and fall of
1975, and completed in the spring of 1976. Based
upon the designs, a complete list of materials as
well as contractor and manufacturers specifica-
tions was prepared. Bids were let as necessary
by Colorado State University under its format
as prescribed by state law and all low bids were
accepted. A summary of all the construction and
associated costs is presented in Table 2 for each
lateral. A detailed description of each lateral's
improvements is presented in the following sections.
Lateral HL E
The HL E lateral contains more than 54 acres of
orchards (apples, pears, and peaches). Work on
this lateral, summarized by Fig. 13, consisted
of the installation of 12.8 acres of overhead
sprinklers on a pear orchard (Fig. 14). The
sprinkler system can be used for frost protection
in the early spring, for cooling in the hot
summer and, of course, for normal irrigations.
Data are beincf collected on other parts of the
orchard in ord^t to compare the traditional
irrigation methods against the sprinkler. In
addition, as part of this system a 1080 linear fact
(LF) , 8" diameter, PVC plastic irrigation line was
installed across a corn field to replace an old
line. This permits a.much more efficient
utilization of,farm land by cropping over it
and the pipeline minimizes maintenance. Two 8"
x 3' Cutthroat flumes were also installed to
measure water applied to the rest of the orchard.
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Table 2. Project Improvements on Lateral Subsystems.
LATERAL
TYP3S OF IMPROVEMENTS
HL C
HL E
PD 177
GV 92
GV 95
GV 160
MC 3
KC 10
MC 30
TOTAL
(32.4 AC)
(88.6 AC)
(68.8 AC)
<59.9 AC)
(195.7 AC)
(194.3 AC)
(9.0 AC)
(133.4 AC)
(34.7 AC)
(816.S AC)
Concrete Ditches (LF)
y
754 1/
620
9149
6229
514
8935 1/
3411
29,612
Buried Plastic Pipelines
Gravity systems (LF)
1260
6780
2680
7746
8360
3460
640
Pressurized systems (LP)
440
1240
1,680 4/
Gated Pipe (LF)
680
2020
1970
400
5,070
Drip Irrigation (AC)
5.4
5.4
Overhead Sprinklers (AC)
12.9
12.9
Sideroll Sprinklers (AC)
10.0
10.0
Drainage Works (AC)
5.5
16.0
28.5
6.3
15.0
2/
71.3
Plastic Drainage Tile (LF)
8750
11470
6425
16265
42,910
Concrete Drainage Tile (LP)
800
800
Flow Measurement (No.)
(3)
(5)
(18)
(3)
(25)
(27)
(3)
(18)
(5)
(105 TOTAL)
Cutthroat Flumes (Ho.)
2
3
2
18
26
2
14
3
70
SO' v-Notch Heirs (No.)
1
1
1
3
Farshall Flumes 3/ (No.)
2
3
1
2
. 2
10
12" Propollor Meters (No.)
1
1
1
3
10" Propyllor Meters (No.)
1
2
3
3" Propel lor Meters (No.)
1
3
1
1
1
7
Other Meters (No.)
1
1
6
Metering Headgates (No.)
1
1
2
Debris Removal Equipment (No.)
1
1
1
3
land Shaping, etc. (AC)
60
28
68
Irrigated Acres (Possible)
26.9
61.5
52.3
46.4
172.0
151.5
7.3
105.4
34.0
657.3
Total Value
$4879.82
$20421.49
$36140.28
$15287.88
$98057.65
$83628.42
$17444.80
$66940.42
$8534.23
$351,335.01
'Cost/Acre
$ 150.61
$ 230.49
$ 525.29
$ 255.22
$ 501.06
$ 430.41
$ 1930.31
$ 501.80
$ 245.94
$ 430.14(AVE)
Cost/ Irr. Acre
$ 181.41
$ 332.06
$ 691.02
$ 329.48
$ 570.10
$ 552.00
$ 2389.70
$ 635.11
$ 251.01
$ 534.5KAVE)
1/ These laterals were part of the earlier lateral lining study and already contained a combined total of approximately 400 LF of concrete ditch.
2_/ This lateral was part of a previous drainage study and already contained approximately 11,000 of plastic drainage tile on 10 acres.
2_/ These fluMs will be removed at the end of the project since they measure field runoff.
±/ The pressurized pipelines are included in the sprinkler systems for cost purposes.
Note: LP « Linear feet
AC - Acres
NO. - Number
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30
High line Canal
ii 12", 240
ii
12", 660'
F/2 Road
I
j
1
JL
r
. Ii
°'!
^ I1
-![
:oo !i
0
L_
440
Scale in feet
¦a
o
o
Q:
^c\j
ro
Legend
Drainage Ditch
Road
Canal
Field Boundary
======= Buried Pipeline
vssssssa Sprinkler Irrigation
ivwww Field Drainage
: Concrete Ditch
F Road
Figure 13. Map of lateral and on-farm improvements under the EL E
lateral system.
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31
The precipitation rate is 0.14 in/hr and the
risers are 15 feet above the ground surface on
a 60' x 60' triangular pattern. Overall sprinkler
system uniformity is 88%. Water is delivered
to a sump (800 gpm) by a previously existing
concrete ditch system (part of which was lined
in a earlier study) and is then pressurized by
a 5C-HP electric pump. The sprinkler appli-
cations are measured by a propeller meter in the
pipeline. The 8" PVC plastic irrigation pipeline
has an 8" propeller meter to record the flow.
An electric-powered, self-cleaning trash removal
screen (1/8" mesh) was installed near the pump
to remove debris from the water going into the
sprinkler in order to reduce plugging problems.
Figure 14. HL E overhead, sprinkler shown operating during
a Spring 1976 frost period.
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32
The overall benefits from the sprinkler are
quite numerous. The irrigations are very
efficient since there is no surface runoff,
deep percolation is minimized, and the entire
13 acres can be irrigated in one 12-hour setting.
Crop cooling for high fruit quality is also an
economic benefit of this system. The frost
protection aspect of this sprinkler is a rewarding
side benefit and is the main reason the sprinkler
was acceptable. The sprinklers are air pollution
free and thus, have larger energy savings
when compared to oil, propane or natural gas
frost protection systems.
Salinity benefits are very evident in the great
reduction of deep percolation. Under the "old"
surface irrigation method the deep percolation
was quite substantial. This salinity control
measure offers a large per acre salinity reduc-
tion, is economically advantageous to the fruit
farmers, and is economically justifiable even
if only for the frost control aspects. The
orchards of the valley have been going out of
production for several years and this type of
irrigation offers great potential to assist the
ailing fruit industry of Grand Valley. For
example, during the spring of 1976 this section
of the orchard was saved due to the frost protec-
tion provided by the sprinkler system (Fig. 14).
The rest of the orchard was virtually frozen out
and will have very little production this year
due to the 22°F low temperature.
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33
Lateral HL C
There are 32.4 acres which could be served by
this lateral, but at this time only 5.5 acres
are actually productive. The improvements made
on this lateral included the tiling of a large
open drain disecting the 5.5 acre field (Figs.
15 and 16) and three flow measurement divices:
two 6" Parshall flumes and one 90° V-notch weir
Figure 15. Old drain through EL C land before tiling.
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34
1;
Figure 16. View of HL C land after drainage improvements.
The large open-interseptor drain was tiled in
cooperation with thr Grand Junction Drainage
District who installed the tile after the project
purchased all materials necessary for the job.
This type of arrangement is basic policy with the
Grand Junction Drainage District^. The tile now
permits a much more efficient field unit for
both farming practices and for irrigation. There
is less farming operation labor involved and
higher irrigation efficiencies have been observed.
Lateral PD 177
Work on lateral PD 177 consisted of installing
a buried piepline distribution system (6780 LF)
with a small amount of cement lining (760 LF)
and installation of two drip irrigation systems
on 5.4 acres of peaches and apples. To demonstrate
the before and after effects of the underground
piping, Figs. 17, 18, and 19 have been included,
and an illustrative summary of PD 177 improvements
are shown in Fig. 20.
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35
Figure 19.
View of PD 177 lateral segment after
completion of pipe installation.
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36
Price Ditch
3
=
i;
r;I1
11
w!
|ii
°!i
— i
M!
1
F Road
Figure 20. Map of lateral and on-farm improvements under
PD 177 lateral system.
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37
The installation of pipelines was done completely
by irrigators on the lateral. The Mesa County
Road Department installed the necessary new
culverts under the roads after all materials and
engineering were provided by the project. The
delivery system above this lateral is a concrete
ditch and buried pipeline arrangement constructed
under an earlier lining study (1010 feet of 10"
pipe and 2600 feet of concrete lining)
The amount of work undertaken by the farmers them-
selves has been significant with many persons
donating their own time and equipment for the
installation. The irrigators also have a very
good understanding of the system operation due
directly to their work on the construction (Fig. 21).
Figure 21. Installation of trickle irrigation
system by irrigator.
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38
Figure 22. Trickle irrigation
°f young peach tree showing
emitters on each side of tree.
Figure 23. Layout of young3 trickle irrigated
peach orchard.
The drip irrigation systems (Figs. 22 and 23)
were installed on 3.4 acres of young peaches
initially and later a second system was in-
stalled on 1.6 acres of mature apples (eventu-
ally to cover another 7.2 acres of apples).
Trickle (drip) irrigation is a recent development
in irrigation which is gaining wide acceptance in
many watershort areas of the world. Water is ap-
plied directly at the plant via an "emitter"
which drips water onto the soil at a very slow
rate (one or two gallons per hour). Irrigations
are on an almost daily basis to replace the
amount of water which the plants have used. There
is virtually no deep percolation, and water use
requirements are usually 1/3 to 1/2 of the more
conventional irrigation methods practiced in the
area. An additional benefit of drip irrigation
is that plant growth is usually much more rapid
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39
Figure 24. Water-powered3 self-cleaning trash
screen for PD 177.
than by other irrigation methods, and in peren-
nial crops, such as orchards, young trees will
often start production much sooner (e.g., one
or two years sooner).
Water measurement on the lateral is a mixture
of 17 propeller meters, Cutthroat and Parshall
flumes and a 90° V-notch weir. Also, a self-
cleaning, water-powered trash screen (1/4" mesh)
was placed at the entrance of the pipeline to
minimize trash and debris problems (Fig. 24).
Six hundred-ten (610) feet of 6" gated pipe is
also in use on this lateral.
Lateral MC 10
This lateral is the third largest (133.4
acres) and had a good water rotation program
developed prior to the project. This same rota-
tion is still in use, but has been greatly facili-
tated by the constructed improvements. This water
sharing developed initially because this lateral
has always been somewhat "water short".
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40
Scale in feet
440
6",200'
I2",630'
D Rood
12",629'
12",
a:
csssazj
s
Drainage Ditch
Road
Canal
Field Boundary
Concrete Ditch
Buried Pipeline
Gated Pipe
Sprinkler Irrigation
Field Drainage
Legend
- o>
ro c
oo
c\J t/>
12" ,1260'
Mesa County
Figure 25. Map of lateral and on-farm improvements under
MC 10 lateral system.
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41
The people on the lateral installed all the pipe-
lines (3040 feet) and have paid for the lateral
linings (8935 feet). Figure 25 depicts the array of
improvements incorporated in this lateral improve-
ment plan. In addition, 28 acres received land
shaping treatment such as leveling. Several acres
of previously idle land were put back into produc-
tion by clearing of trees and shrubs and land
leveling. The Grand Junction Drainage District
also installed 16,265 feet of drainage tile on 15
acres of this lateral (Fig. 26).
An automated cut-back irrigation system (Fig. 27,28)
was also installed on 10 acres of barley. This same
10 acres is included as part of the field drainage
construction. It should be mentioned that even
though the cut-back irrigation system is installed
on a problem area in this project, it is also highly
recommended for good, high production fields. Nine-
teen hundred-seventy (1970) feet of 6" and 8"
gated pipe are also in use on this lateral.
Figure 26. Grand. Junction Drainage District
installing field drainage system.
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42
Figure 27. Automatic cutback irrigation system
installed under MC 10 lateral system.
Figure 28. MC 10 cutback irrigation system in
operation.
At this time, there are 18 flow measurement devices
on this lateral. These irrigators have been
quite willing to use flow measurement in their
irrigation, largely due to their previously
developed mutual water sharing program.
Lateral MC 3 0
This one-landowner lateral was part of the earlier
study on field drainage and contains 11,000 feet
of plastic drainage tile on 10 acres (Fig. 29).
Further improvements on this lateral include
3411 feet of concrete linings, 640 feet of 8"
buried plastic pipeline and 400 feet of 6" gated
pipe. There are five flow measurement structures
on this lateral.
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43
Legend
Concrete Ditch
Buried Pipeline
Gated Pipe
Field Drainage
1
1
400
I
Scole in feet
ro
OJ
3
D Road
°
*
=ao!!
6 ,400
(moved from side to
side )
mm
m
ma
Figure 29. Map of lateral and on-farm improvements under
MC 30 lateral system.
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44
Lateral MC 3
This lateral is quite small (9.0 acres) but is one
example of the most saline land which could be
found in the Grand Valley. In the early 1900's,
this farm was a very productive pear orchard;
however, since that time a high water table caused
by over-irrigation on higher lands and seepage
from the Mesa County Ditch has completely put this
land out of production. The soil salinity is
high and contains large amounts of sodium salts or
"black alkali". This lateral was selected in
order to see if highly saline agricultural lands
could be reclaimed without seriously raising
salinity levels in the water courses.
Previously, the Mesa County Ditch, which runs across
the upper boundary of this farm, was lined with
gunnite. The first step was to install field drain-
age to alleviate the high water table and provide
a mechanism to leach the salts from the soil. The
drains were constructed on a 40-foot spacing on
6.3 acres (6425 feet of tile). The tile was in-
stalled by the Grand Junction Drainage District.
The second step was to install a type of irriga-
tion which could apply light, frequent irrigations
which would force the salts to move down in the
soil profile. One type of irrigation which satis-
fies these criteria is automated cut-back irriga-
tion (Figure 30). This type of irrigation can
apply light amounts of water quite frequently
and facilitate very high efficiencies. An
automated cut-back system was installed on this
lateral (514 feet of concrete ditch).
J
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45
Figure 30. Automatic outback irrigation system
for MC 3 lateral.
Legend
— Drainage Ditch
— Road
Canal
Field Boundary
iwnxiWvVTO Field Drainage
= Concrete Ditch
I
1
440
I
Scale in feet
Figure 31. Map of lateral and on-farm improvements under
MC 3 lateral system.
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46
Due to the extremely saline conditions, progress
toward reclamation has been slow and a return to
full production is expected to take several
years. Water passing through the drainage field
has shown that the system is working as designed
and the land will eventually be productive. A
summary of improvements under this lateral is
shown in Fig. 31.
Lateral GV 95
Lateral GV 95 (Fig- 32) is the largest lateral
studied under this project and also has the largest
expenditures for improvements. It is basically
a buried plastic pipeline and a concrete lined
distribution system. There are considerable
on-farm improvements such as gated pipe, concrete
lined head ditches, field drainage and a side roll
sprinkler (Fig. 33). There is also a rather exten-
sive tailwater collection and reuse system. This
lateral contains approximately 70 acres which was
consolidated from two other laterals to minimize
duplication of ditches and other structures.
All of the matching monies for construction of the
mainline distribution systems were paid by the
lateral users, and the work was done by outside con-
tractors. The matching money was collected (by the
lateral users) through charging each person $200
for the first share of water and $40 for each addi-
tional share (any money left over would go for fu-
ture 0 & M costs). The money was then put in excrow.
Most of the on-farm improvements were also paid
for in cash rather than labor. As a consequence
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47
^r"nd valley Canal
l| 15" ,800'
E Rood
Legend
Drainage Ditch
Road
Canal
Field Boundary
Concrete Ditch
Buried Pipeline
Gated Pipe
Sprinkler Irrigation
Field Drainage
| |l ^ 23i,|[J2" .995- |l |
i ¦ jl 1 12". 1345'
' - s'lStsHpr^
Figure 32. Map of lateral and on-farm improvements under
GV 95 lateral system.
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48
of this lack of direct involvement in the con-
struction, many of the lateral users did not have
as good an understanding of the system operation
as did other laterals who directly participated
in the construction.
Flow measurement is accomplished by means of five
propeller meters and 18 Cutthroat flumes. There
are also some Parshall flumes and a 90° V-notch
weir for a total of 2 5 measurement structures.
A total of 2020 feet of 6" gated pipe is in
use on this lateral and 16 acres received field
drainage installation (8750 LF of 4" polyethylene
drainage tile). Another 60 acres received land
shaping and leveling treatments.
On one 10-acre field, a short (520 feet) sideroll
sprinkler was installed having a precipitation
rate of 0.28 in/hr and a distribution uniformity
of 88%. Water is delivered to a sump via the
concrete lined distribution system. A 10-HP
single phase pump then pressurizes the water
Figure 33. Sideroll sprinkler operating under
GV 95 lateral.
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49
(110 gpm) and transports it through a buried pipe-
line to the sprinkler. Irrigation is divided into
thirteen 8- to 12-hour sets. The cost per acre is
approximately $780.00, however, this system could
easily be expanded to a 40- or 60-acre field at
little additional cost thereby greatly reducing
the per acre cost. An electric self-cleaning
trash screen (1/8" mesh) similar to the one shown
earlier was installed at the entrace to the sump
pump to minimize sprinkler plugging. This system
has worked quite well and the very pleased owners
have stated that the increased yields due to the
greater uniformity will more than pay for the
electricity costs.
Lateral GV 92
This lateral (Fig. 34) was the last lateral con-
structed and was completed in the spring of 1976.
Approximately half of the land originally under
this lateral was consolidated into another lateral
(GV 95) to minimize the duplication of ditches
and facilities.
The system installed on this lateral is a concrete
ditch (Figs. 35 and 36) and pipeline delivery
system. No on-farm construction was implemented.
This was done in order to determine the salinity
effectiveness of making only lateral distribution
improvements.
Water measurement at the headgate is accomplished
by means of a metering headgate. Water division
is regulated internally by means of two 8" x 3'
Cutthroat flumes.
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50
X
|
Jk
ir
Grand Valley Canal
0 220 440
1 i i
Scale in feet
Legend
Drainage Ditch
Road
Canal
Field Boundary
Buried Pipeline
Concrete Ditch
Figure 34. Map of lateral and on-farm improvements under
GV 92 lateral system.
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51
)
Figure 35. GV 92 lateral before Figure 36. View of GV 92 lateral
concrete lining. after concrete lining.
The 10" plastic pipe was installed by various
irrigators on the lateral and School District
51 (who owns land under this lateral), and they
all participated on a cost sharing basis on the
concrete ditch.
Lateral GV 160
This is the second largest lateral on which work
was done and it has some of the worst salinity
problems encountered in the Grand Valley (Fig. 37)
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52
Legend
Drainage Ditch
==^=^= Road
hmhhhbmh Canal
Field Boundary
===== Concrete Ditch
------------ Buried Pipeline
Gated Pipe
Field Drainage
10", I 2", a 15
PVC Pipe,
Concrete Pipe ,
8", 200' Pipe
( not shown )
ft
0 220 440
1 1 1
Scot* in feet
E Rood
Road
/
D Rood |
7 1
/ I
Figure 37. Map of lateral and. on-farm improvements under
GV 160 lateral system.
/
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53
The land is very saline and agricultural production
is quite low. Treatment included the installation
of 8020 feet of buried plastic pipeline (installed
by persons on the lateral) and 6229 feet of lined
concrete ditch. In addition, 28.5 acres received
field drainage. Another lateral (GV 161) was con-
solidated into this lateral because the two
ditches paralleled each other (no more than 10
feet apart) for 3/4 of a mile with no turnouts in
either lateral.
There are 27 measurement devices on this lateral
to assist in the distribution. There were very
little on-farm improvements made other than the
drainage.
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54
The Agricultural Engineering Department1s
efforts in the Grand Valley have been applied
in an area of unique characteristics. Indivi-
dual fields are small and most of the local
people are primarily supported by jobs outside
of agriculture. The area is severely affected
by salinity and the expanding urban center of
Grand Junction.
The associations with the local people have
been for the most part interesting and on a
positive note. However, the local conditions
described previously, and our attempts to
minimize formal agreements with their attendent
limitations on flexibility and their large
time requirements have not been without some
difficulties. Part of the construction was
delayed by poor weather and interfered with
farming operations in a few cases. At other
times, communication between project personnel
and the local people was not entirely effictive
and some disappointments and misunderstandings
developed. Most of these have been remedied,
or will be remedied by the end of the project.
Although our own experiences have been satisfying
for the most part, we too have been occassionally
frustrated by the items noted above. The involve-
ment by the participants in the actual management
and operation of the lateral systems after
completion of construction has been less than
we had hoped. Interestingly enough, in those
cases where the local people participated most
during construction, the greatest involvement
after construction has been observed. We
In
Retrospect
-------
55
believe future salinity control projects should
involve participation by local water users.
Water users should conduct as much of the improve-
ments as possible to insure workability
afterwards.
During early 1977, the final reports on this
research program will be completed and then
printed by the U.S. Environmental Protection
Agency. These reports will describe the cost-
effectiveness of various improvements in reducing
the salinity in the Colorado River. Thus, the
results should serve as a guide in implementing
a salinity program that is expected to cost
more than $100 million for Grand Valley, alone.
The implementation of the salinity program for
Grand Valley is expected to begin in the fall
of 1977. Two government agencies—the Bureau
of Reclamation and Soil Conservation Service—
will be responsible for working with the local
water users in undertaking and completing this
program. We wish all of the participants
success in both reducing the salinity in the
Colorado River and increasing the agricultural
productivity of Grand Valley.
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