IRRIGATION RETURN FLOW WATER QUALITY
AS AFFECTED BY
IRRIGATION WATER MANAGEMENT IN THE
GRAND VALLEY OF COLORADO
Final Report
of
Research Conducted by the
Agricultural Research Service
United States Department of Agriculture
Fort Collins and Grand Junction,
Colorado
for
United States
Environmental Protection Agency
Region VIII
Denver, Colorado
October 1976
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IRRIGATION RETURN FLOW WATER QUALITY
AS AFFECTED BY
IRRIGATION WATER MANAGEMENT IN THE
GRAND VALLEY OF COLORADO
By
Harold R. Duke
E. Gordon Kruse
Sterling R. Olsen
Daniel F. Champion
Dennis C. Kincaid
U. S. Department of Agriculture
Agricultural Research Service
Colorado - Wyoming Area, Western Region
Fort Collins, Colorado 80522
Grand Junction, Colorado 81501
Project Officers
Mr. George Collins
U. S. Environmental Protection Agency
Region 8
Denver, Colorado 80203
Dr. C. E. Evans
U. S. Department of Agriculture
Agricultural Research Service
Western Region
Colorado - Wyoming Area
Fort Collins, Colorado 80522
Interagency Agreement No. 12-14-5001-6037
EPA IAG-D4-0545
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TABLE OF CONTENTS
Page
LIST OF FIGURES. . . . . . . . . . . . . . . . . . . . , . , , iv
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . V
SECTIONIIntroduction . . . . . . . . . . . . . . . . 1
Statement of theProblem . . . . . 1
Ongoing ARS Research in the Grand Valley. . . . . . . . . 1
Objectives of Current Study . 2
SECTION II Summary of Results . 3
SECTION IllConclusions. . 5
Variables Needed to Predict Effects of Irrigation on Quality
of Return Flows . . . . . . . . . . . . . . . . . . . . . . . 5
Reduction in Water and Salt Losses Achievable by Improved
Irrigation Technology. . . . . . . . . . 6
Mechanisms of Modification of Return Flow Water Quality . . 6
SECTION IVRecotnmendations . . . . . . . . . . . . . . . . . . . . 8
SECTION V Description of Methods Used. . . . . . . 10
Components of Water Balance . . . . . . . . . 10
Delivery Losses . . . . . . . . 10
Applied Irrigation Water . . . 11
SoilWaterMeasurements . . . . . . . . . . 11
Deep Percolation Losses. . . . . . . 11
VacuumExtractors .. 12
Nonweighing Lysimeters. . . . 12
Soil Chloride Profiles . . . . . 14
Evapotranspiration........ ... . 14
ii
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C S S
S C S I
91
Page
Water Analyses. . . . . . . . . . . . . . . . . . . . . . . . . 15
SedimentConcentration. .... eels....., ... 15
Chemical Analyses. . . . . . . . . . . . . . . I 17
SECTION VI Description of Field Sites. . . . . . . . e 19
Intensive Study 20
Soil Chloride Profiles 20
Direct Measurement of Deep Percolation. 24
Measurements of Irrigation Application and Runoff 24
Evapotranspiration 24
Lateral andCana lSeepage . .. . . . 28
Drain Flows andGroundwater . . . . . . . . . . . . . . . , , 30
SECTION VII Results 32
Chloride Sampling to Infer Leaching Fraction 32
Direct Measurement of Water Balance Components. . . . . . . . 41
Furrow Irrigation InflowOutflow Studies 41
Quantity and Quality of Measured Deep Percolation. . . . . 55
Measurement of Evapotranspiration. 60
Evaluation of Tailwater Runoff . . . . . e . . . 65
Lateral and Canal Seepage Losses 70
Ground Water and Return Flow. . . . . . . 76
SECTION VIII Applicability of Methods to Similar Areas . . . 85
SECTIONIXReferences.. ,,, 89
SECTIONXAppendix . .
iii
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LIST OF FIGURES
Figure No. Page
1 Schematic of vacuwn extractor installation 13
2 Operational diagram of hydraulic lysimeter 16
3 Sketch of experimental field plots and instrumentation
at intensive study site 22
4 Location of fields sampled for chloride analysis 23
5 Location of vacuum extractors 25
6 Location of irrigation application and tailwater
runoff studies 27
7 Location of canal and lateral seepage studies 29
8 Location of wash discharge studies and geologic
investigation 31
9 Hypothetical Cl concentration profile of soil
solution under leaching conditions 33
10 Comparison of estimated potential ET with measured
ET from alfalfa 62
11 Ratio of evapotranspiration to potential ET as a
function of time 64
12 Drill hole locations. Little Salt WashAdobe Wash
Areas 79
13 Response of water level in observation well to
seepage 80
lv
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LIST OF TABLES
Table No. Page
1 Chemical analyses conducted on various samples 18
2 Approximate acreage and proportionate extent of
major soil series in the Grand Valley 19
3 Site locations 21
4 Irrigation application and tailwater runoff studies 26
5 Composition of irrigation water at intensive study
site 34
6 Weighted chloride concentration in irrigation water 35
7 Chloride concentrations at 20% (dwb) soil water
content 37
8 Average leaching fraction as calculated by chloride
profile technique 40
9 Furrow irrigation studies, instrumentation summary 42
10 Furrow irrigation studies 44
11 Hydraulic characteristics of furrow flow at selected
sites, 1975 average 49
12 Measured intake rates, Grand Valley soils 50
13 Measured intake rates, Spring 1976 52
14 Deep percolation measured from vacuum extractors and
nonweighing lysimeters, 1975 56
15 Comparison of leaching fraction calculated by various
techniques 58
16 Weighted mean chloride concentration of percolate
collected in vacuum extractors 59
17 Taliwater runoff from study sites In Grand Valley 66
18 Chemical and sediment analyses of irrigation water,
1975 68
v
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Table No. Page
19 Estimated average annual water balance, Grand Valley 70
20 Sediment concentration as a function of runoff time 71
21 Results of seepage studies on major canals, Grand
Valley 72
22 Lateral seepage losses below GHC, 19751976 74
23 Drain flow and salt measurements, winter 19751976 82
24 Water composition from adjacent sites in Persigo,
Little Salt, and Indian Wash drains, Grand
Junction, Colorado 83
Al Chemical analyses of vacuum extractor samples 92
A2 Water levels in ARS (Schneider) wells 114
A3 Chemical analyses of water samples from ARS
(Schneider) wells 116
A4 Chemical analyses of drain flows 122
vi
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SECTION I
INTRODUCTION
Statement of Problem
In the late spring of 1974, officials of the U. S. Environmental
Protection Agency, Region 8, in Denver, Colorado contacted research-
ers of USDA Agricultural Research Service, Fort Collins, Colorado
regarding the possibility of an interagency research program rela-
tive to the quality of return flows from Irrigation in the Upper
Colorado River Basin. At that time, the EPA foresaw upcoming regu-
lations concerning the regulation of return flow from irrigation
and expressed considerable interest In evaluation of the relation
between irrigation practice and quality of return flows. Of spec
if ic interest were identification of the variables needed to effect-
ively detect and manage irrigation return flows and evaluation of
the best practical irrigation technology applicable to the area.
Ongoing ARS Research in the Grand Valley
In March 1973, the Agricultural Research Service entered into
an agreement for partial research funding by the Bureau of Reclama-
tion, U. S. Department of Interior to evaluate salt in return flows
and develop irrigation techniques to reduce salt loading. One of
the primary objectives of this study is to provide a field test of
a low leaching concept conceived by personnel of ARSs U. S.
Salinity Laboratory, Riverside, California, whereby frequent light
irrigations are applied so as to maintain adequate water for crops
and at the same time reduce the leaching fraction sufficiently to
induce precipitation of salts concentrated by plant water use.
This effort required establishment of a work location in
Grand Junction and assembly of a permanent staff. The current lo-
cation staff consists of a soil chemist, an agricultural engineer,
three technicians, a secretary, and seasonal help as required.
With the help of U. S. Salinity Laboratory personnel, the Grand
Junction and Fort Collins staff installed a center pivot irrigation
system, covering 26.5 acres, with instrumentation to measure water
application, percolation, evapotranspiration and soil salinity
changes under each of two replications of three water treatments.
Similar instrumentation was provided for four furrow irrigation
plots.
Subsequently, the study was expanded to include seepage meas-
urements in the main canals and in the open drains, geologic and
groundwater characterization in the vicinity of the intensive
studies, and analysis of wintertime flow and chemical concentration
in the washes. These latter studies were designed primarily to
attempt to identify the mechanism by which return flows reach the
river.
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Copies of annual progress reports are available to cooperating
agencies.
Objectives of Current Study
The current study was designed to meet the specific needs of
the Environmental Protection Agency consistent with the interests
and research goals of ARS The research is complementary to other
ongoing ARS studies in the Grand Valley and some phases are an
extension to a wider range of soils and management practices of
studies begun under the USBR project. The specific objectives of
the current study are:
1. To identify the variables needed to predict the effects of
deep percolation, tailwater runoff, and lateral seepage
on the quality of return flows. Includes evaluation of
both quantity and quality of the various components of
the field water balance.
2. To define the effect of irrigation water management on the
quality of runoff and deep percolation leaving the farm
unit and determine the reduction in both water and salt
losses that can be achieved by improved irrigation
technology.
3. To identify the mechanisms by which the salt load of
return flow water is modified after it leaves the farm
unit and moves toward the Colorado River and attempt to
determine the most practicable methods of controlling
further salt accretion between the farm unit and the
river.
4. To evaluate the experimental methods used in the above
studies with regard to their applicability in other
similar irrigated river valleys.
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SECTION II
SUMMARY OF RESULTS
As discussed elsewhere in this paper, the results of some
phases of the study varied widely throughout the valley. Only
total and/or mean values are reported in this section. For more
detailed analyses, including statistical interpretations of the
variations measured, the reader is referred to the appropriate
section in the text of the report. The location of supporting
discussion is indicated by page numbers in parentheses.
It is concluded that a major source of subsurface return flow
is seepage from the unlined delivery system, although it may enter
the river through the natural drains ( 70). The canals and lateral
ditches combined are estimated to recharge about 100,000 acre feet
of water annually ( 70). If all this water passed through the
cobble aquifer, which it does not, and returned to the river at
the salinity of the aquifer water, it would account for virtually
all the salt load of the Colorado River attributed to the Grand
Valley. A portion of this water, however, returns to the washes
at a lower salinity level than occurs in the aquifer. The winter
base flow, which includes water from all seepage sources, in nine
washes monitored is estimated to return salt at a rate of 104,000
tons per year ( 76). Extrapolating these data to all drains in the
valley and considering that high groundwater levels undoubtedly
result in larger groundwater flow into the washes during the sununer,
results in an estimated total open drain contribution at least
twice the value reported. In any case, it appears that the direc-
tion and salt concentration of seepage return flow are dictated by
geologic conditions, and are practically independent of the rate
of seepage ( 70).
Infiltration rates of irrigated soils were found to be quite
variable, with respect to both time and location. Cumulative 12
hour infiltration ranged from 3.4 to 13 inches during the first
irrigation of the season, and approximately half that value (1.6 to
6.9 inches) during subsequent irrigations ( 41). Since current
practice dictates extended irrigation periods during the first
Irrigation to wet the seedbed, it is probable that a large fraction
of the leaching occurs at that time.
Deep percolation losses range from virtually none in parts of
the western end of the valley to quite high values east of Grand
Junction. For the valley as a whole, the estimated leaching frac-
tion was not large, averaging about 0.13 ( 55). Thus, the total
volume of percolate is about 28,000 acre feet per year, or 22 of
the total estimated seepage ( 55). As was the case with canal
seepage, the ultimate quality of percolating water is not propor-
tional to the volume.
Of the total irrigation water applied to the fields, tailwater
runoff averaged 33.6 percent ( 41). These large amounts of runoff
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are necessitated by the generally low infiltration rates and the
necessity of wetting across to obtain seed germination. This
runoff water carries an average of 2.2 tons sediment per acre foot
of runoff water, resulting in an average erosion rate of 0.02 inches
annually. The sediment and a small amount of phosphorous were the
only detectable evidence of deterioration of water quality in the
runoff ( 65). Pesticide concentrations were not taken into consid-
eration.
Crop evapotranspiration from corn during the growing season
was measured at about 32 inches under fur pw irrigation and 27
inches under sprinkler irrigation C 60). One very significant con-
clusion is that airborne evaporation from i-the sprinkler nearly
equals the reduction in ET under the sprinkler. Since a portion of
the net solar energy is used to evaporate airborne water directly,
a correspondingly smaller amount of energy is available for trans
piration. Thus, direct evaporation cannot be construed as wasted
water application. During the period of full crop cover, measured
ET was about 30 percent greater than estimated by the ABS schedu.l
ing program ( 60). This has led to intensive efforts at recalibra
tion of the coefficients used in the computer program to represent
conditions in the Grand Valley.
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SECTION III
CONCLUSIONS
Variables Needed to Predict Effects of Irrigation
on Quality of Return Flows
For purposes of this report, return flows may be logically
divided into two distinct components. The first remains as surface
water throughout its course from diversion from the river to its
return to the river via the natural washes and constructed surface
drains. During the irrigation season, a varying but substantial
portion of diverted water is deliberately spilled from canals into
these drains for control of canal delivery. In all cases studied,
the natural drains were observed to increase in discharge with dis-
tance downstream from the Government Highline Canal (i.e., the
upper limit of the irrigated area), even during the winter when
groundwater levels are lowest ( 76). This indicates that water
table elevations are higher than surface water levels in the drains
and that deliberately spilled water does not enter the aquifer in
significant amounts. Thus the spillage se would not be expected
to result in significant salt loading of the river.
Tailwater runoff from irrigation was not found to dissolve a
statistically significant amount of salts from the soil for trans-
port to the river ( 65). This tailwater runoff, however, does
remove significant amounts of sediment and small, but detectable
amounts of phosphorous associated with this sediment ( 65). Thus,
from the standpoint of salt contribution, the surface water component
appears to be a minor contributor to degradation of return flow,
except for the deep seepage that may occur from tailvater ditches
and shallow drains.
The second component of return flow is that water which per-
colates through soil material prior to entering the river, either
as direct underf low or via the surface drains. Although the path
of this water, and the geologic materials it contacts, varies con-
siderably, it appears to equilibrate with the soluble gypsum and
calcite present. As percolation rates are reduced and transit time
of groundwater increases, other soluble salts will undoubtedly
increase in concentration somewhat. However, since the groundwaters
are, for the most part, saturated with gypsum and calcite, the net
long term result of reduced seepage will be a reduction in total
salt load.
Control of salt loading is dependent almost solely on control
of the water itself. As mentioned in the previous section, canal
and lateral seepage appear to be the major source of this subsurface
component of return flow ( 70). Deep percolation is affected by
the variable infiltration rate of the soil, by poor provision for
water measurement, and by the long infiltration opportunity time
needed to apply required amounts of water.
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Reduction in Water and Salt Losses
Achievable by Improved Irrigation Technology
Although not technically water losses, the surface return
flows from irrigation can be eliminated by application of available
technology. Conversion to a strict demand diversion would eliminate
the necessity for canal regulation by spillage. Tailwater recovery
systems, advanced automation devices, or possibly an adaptation of
the dead level irrigation concepts used in parts of the Southwest
would allow elimination of tailwater runoff and its associated
sediment.
It appears from our studies that an impervious water delivery
system would provide the most significant reduction in both quantity
and quality of return flow. Estimated canal and lateral seepage
could, if returned to the river at the salinity of the aquifer,
carry much more salt than the total estimated salt loading through
the Grand Valley. Even at the average measured base flow salinity
of EC 4.4 mmhos/cm (much lower than the salinity of the cobble
aquifer), the combined canal and lateral seepage of 100,000 acre
feet annually would return in excess of half a million tons of
salt ( 70).
Although we must conclude from our studies that deep percola-
tion is not the major source of return flow ( 55), there is room
for improvement, particularly on some soil types. Perhaps modified
tillage practices to leave crop residue near the surface or modified
planting practices to reduce the need for long irrigations, partic-
ularly early in the season when infiltration rates are high, would
prove viable improvements. As applied in the Southwest, dead level
irrigation allows very uniform distribution of small applications
of water, such as needed for germination. These concepts are as
yet unproven for the Grand Valley, but are the subject of ARS
research being initiated at this time.
However, regardless of the degree of control attainable over
water application, some leaching must occur to attain a favorable
salt balance in the soil. Although we have sustained production
under very low leaching fractions under the sprinkler in the Bureau
of Reclamation study, it is doubtful whether adequate salt control
can be attained under surface irrigation with leaching fractions
less than 0.1 because of natural variability of soils within a
field. At this rate, leachate return flows would exceed 15,000
acre feet per year, with an accompanying salt load of from 80,000
(at EC of washes) to 200,000 (at EC of saline aquifer) tons per
year.
Mechanisms of Modification of Return Flow Water
Surface water return flows apparently suffer little degradation
in passing from the canals back to the river via the natural washes.
Tailwater runoff from irrigated fields carries substantial amounts
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of sediment, but the only ionic constituent showing a detectable
increase in concentration is phosphorous C 65). Though this sur-
face return flow does not technically constitute a loss of water
from the system, large acreages surrounding the washes lie waste
and support only weeds and phreatophytic plants. These plants
undoubtedly consume a significant amount of water for nonproductive
plant growth. The tortuous path of the washes and the extreme
depth (30 feet or more in many places) necessary to transport
spillage and occasional storm runoff from the desert above result
in removal of much otherwise irrigable land from production.
Both deep percolation from irrigated land and seepage from
the delivery system, which is apparently the most significant
source of return flow ( 70), enter the groundwater system. Where
the shale is intersected by ditches or overlain by shallow soils,
percolating water enters directly into a bedded, jointed, quite
permeable shale zone capped with impervious clay derived from the
surface of the shale ( 76). Within this zone, water moves in very
unpredictable paths, and may retuTn after a short time directly to
the washes. It may also move downslope to emerge in lowerlying
canals, or to rise through discontinuities in the clay cap into
the cobble aquifer or the shallow overlying soils. Deep percolat-
ing water may be intercepted by discontinuous clay lenses resulting
in lateral flow or percolate to the Mancos shale over which it
flows downslope to drain into the washes or enter the very saline
cobble aquifer. Regardless of the path of subsurface return flow,
abundant soluble salts are present in the geologic strata. We
conclude that the salt concentration in the subsurface return flows
will be increased less by each successive increment of reduction
in seepage, so that reduction of seepage (percolation) volume will
result in reduction of total salt mass returned to the river.
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SECTION IV
RECOMMENDATIONS
At the outset, it must be emphasized that the following recom-
mendations are based solely on the physical benefits to be derived.
The scientists involved in this research are well aware that econ-
omic, social and legal restraints will influence the degree to
which these recommendations can be implemented, at least within the
immediate future.
The one change that would allow most effective improvement of
irrigation in the Grand Valley would be implementation of a demand
delivery system. Such a system, requiring individual water orders
be placed at least as far in advance of need as the canal transit
time, would eliminate the need for canal spillage, and eliminate
much of the lateral and farm ditch seepage resulting from continuous
delivery. The present surface water law gives little incentive to
efficient water management, and in fact penalizes the water right
holder who attempts to improve efficiency, as he apparently cannot
receive restitution for that portion of his right not diverted.
During peak use periods, the entire capacity of most canals is need-
ed to satisfy ET, yet the remainder of the season much diverted
water is not needed and returns to the river. A demand system would
allow onfarm delivery, on a rotational basis, of sufficiently large
flow rates to effectively utilize automated irrigation systems and
other advanced management techniques.
If one accepts our conclusion that the primary source of ground-
water contribution is seepage from the delivery system, it follows
that the greatest improvement in return flow water quality would be
realized from an impervious delivery system. To most effectively
integrate a demand delivery system and provide for implementation
of improved onfarm water management, we recommend a system based
on lined open canals for the primary distribution system with closed
conduit lateral delivery from the canals. Such a system would pro
vide precise control of distribution from the lateral and provide
low pressure heads necessary for operation of underground and/or
gated pipe distribution on the farm. Such a system has many bene-
fits to the irrigator as well as the water supplier. Besides re-
ducing seepage losses, it eliminates weed growth and associated
maintenance costs and recovers otherwise productive land for crop
production. Elimination of field ditches, for example, recovers
not only the area occupied by the ditch, but also the turn row need-
ed below the ditch, an estimated 3 acres per mile of ditch. Such a
system can also follow a more direct route from canal to farm,
eliminating many small areas presently uneconomical to farm.
Computer scheduling of irrigation has been proven in many areas,
and is certainly adaptable to the Grand Valley. Obstacles to its
iimnediate success in the valley are lack of water delivery on d in nd
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and lack of reliable methods of water measurements. Any system
improvement must include provision for readily determining amount
of water delivery, and, if permitted, of tailwater runoff. An ex-
tension of the scheduling concept is the subject of current ARS
research at Fort Collins. This extended concept integrates irriga-
tion scheduling with systems analysis to give optimum allocation
of water to those delivery points at which it is most urgently
needed. Such an approach, with the prediction presently built into
the scheduling program, would provide not only a farm management
tool but also an invaluable canal management tool. Implementation
of such an approach, however, will obviously require a change in
both social and legal attitudes.
Numerous cultural practices proven successful in other irri-
gated areas hold promise for improving Irrigation In the Grand
Valley. Several areas in the desert Southwest utilize large flow
rates into level basins to obtain very uniform water application
with no tailwater runoff. With large flow rates, a predetermined
volume of water can be applied in a short time and allowed to in-
filtrate after inflow has ceased. Thus application depth can be
precisely controlled. Minimum tillage or notill practices adopted
in many areas may prove feasible to increase infiltration, control
crusting and reduce sediment load. Modified planting practice to
place the seedbed nearer to the water furrow would, if successful,
greatly minimize the need for long irrigation times to obtain ger-
mination in the spring when infiltration rates are high. Each of
these practices is yet to be proven before recommendation in the
Grand Valley, and is a current subject of ARS research In the area.
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SECTION V
DESCRIPTION OF METHODS USED
Components of Water Balance
Before one can determine the effects of various hydrologic
components of irrigation on the ultimate quality of return flows to
the river, the magnitude, thus the relative importance, of each of
these components must be determined. Traditional methods of on
farm water balance determinations involve direct measurement of
surface water movement in the liquid phase, estimates of vapor flux
(primarily evapotranspiration from cropped areas) and assuming the
remainder Is lost to percolation. As a result, all measurement
errors associated with irrigation application are lumped into the
percolation component. These errors can well be several times
greater than the percolation itself. For this reason, attempts
were made to determine each component of the water balance mdiv-
idually for the current study. Description of the techniques used
to quantify the various hydrologic components follows.
Delivery Losses . Water delivery losses in the Grand Valley
irrigation system are rather unique because of the continuous flow
method of operation. River diversions may vary with season, but do
not vary with daytoday Irrigation demand. As a result of irreg-
ular irrigation demand, excess canal flows are spilled directly
into the drainageways (either natural or man made) through which
the water returns to the river. Although these drains do receive
saline water from the groundwater, seepage measurements made as a
part of the USBR study Indicate that little water enters the aqui-
fer from the drains. Thus, this spillage water itself contributes
insignificantly to salt loading of the river. For this reason,
measurements of this spillage were not attempted as a part of this
study.
Evaluation of delivery losses was confined to measurements of
seepage from the main delivery canals and laterals serving the
farmer. Because the canals flow continuously during the irrigation
season, tests were necessarily confined to pre and postirrigation
season. Tests were conducted on one lateral using flumes for
inflowoutflow measurements over a reach of canal. Such measure-
ments were impractical in most cases because the expected error of
flumes approaches or exceeds the expected seepage rate over reason-
able lengths of canal. The majority of seepage tests were conducted
by constructing temporary dams across both ends of a canal reach,
filling the resulting pond with water, observing the rate of water
surface decline, and correcting for evaporation loss. Fall ponding
tests were conducted immediately after canals were shut down, using
remaining canal water to fill the ponds. Spring tests were conducted
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on short reaches, as river water had to be hauled by truck to fill
the ponds prior to first canal diversions.
Applied Irrigation Water . Studies to determine efficiency
cf furrow Irrigation application were conducted on a total of 27
fields throughout the Valley, representing eight major soil types.
To allow accurate determination of advance times and assure uniform
furrow flows, applied irrigation water was measured with a special
orifice box serving either two or four furrows. This box was in-
stalled and leveled Immediately adjacent to the field ditch so that
the farmer could set his siphon tubes into the orifice box to irri-
gate the test plots just as the remainder of the field. The orifice
boxes were fitted with water stage recorders to allow determination
of time, rate and volume of irrigation application. Two fields were
equipped with flumes for inflow measurements, as the ditch location
was unsatisfactory for the orifice box. Individual furrow flumes
were used at one site, a trapezoidal flume In the delivery ditch
at the other site.
Because infiltration rates are generally quite low in the
Valley, the typical farmer irrigation practice is to apply water at
such a rate that it reaches the end of the furrow in four to six
hours, then continue irrigation for a total of 24 to 48 hours. As
a result, considerable amounts of irrigation water leave the field
as tailwater runoff. This taliwater is subsequently reapplied to
lower fields, or returns to the river via the surface drains. All
study sites were equipped with flumes having water stage recorders
to measure tailwater runoff from the area of lnf low measurements.
These data allowed determination of inflow, outflow, and applica-
tion, and in most instances rate of advance, from which intake
rates could be estimated.
Soil Water Measurements . A further component of the water
balance picture Is the amount of irrigation water stored in the
soil for subsequent plant use. Soil water storage by irrigation
was estimated by periodic determination of water content in the
root zone. Eight sites were Instrumented with three access tubes
each for neutron moisture measurement. Water content was measured
In each field before and after each Irrigation. Interference with
the cropping procedures, shallow soils, and limited personnel pro-
hibited neutron measurements In all fields under study. Soil water
content was determined periodically by gravimetric methods to
supplement neutron data, to check neutron calibration, and to provide
samples for soil chemical analysis.
Deep Percolation Losses . The most difficult parameter of
the water balance to measure directly is the percolation of water
beneath the root zone. Deep percolation is a very important com-
ponent of the water balance, since It is this water, along with
seepage from canals, that has the best opportunity to dissolve
salts from underlying formations and subsequently return these
salts to the river. Because it Is so difficult to measure directly,
deep percolation is most often calculated by measuring or estimating
the other components of the field water balance, then solving the
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continuity equation for the deep percolation. This procedure has
the effect of lumping all measurement errors into the value of the
deep percolation. Since this parameter is usually (or at least
desirably) a small fraction of the applied irrigation water or
evapotranspiration requirement, the percentage error of deep per-
colation estimates by this technique is frequently large. Numerous
techniques for independent estimates of deep percolation were eval-
uated as a part of this study.
Vacuum Extractors . A direct measurement device developed by
Duke and Haise (1973) was installed at five of the sites at which
irrigation application efficiencies were studied. This device,
called a vacuum extractor, consists of a pair of porous ceramic
tubes placed in the bottom of a soil filled, open topped metal
trough. This trough, with a rubber air bag attached to the bottom,
is installed in a rectangular shaped, horizontal tunnel formed in
undisturbed soil beneath the crop root zone as shown In Figure 1.
After the trough was placed in the tunnel, the air bag was inflated
to press the open top of the trough against the undisturbed soil
above to maintain hydraulic contact. Vacuum applied continuously
to the candles intercepts percolating water, presumably at the
rate of natural percolation, and θollects this percolate in a bottle
for subsequent measurement and chemical analysis.
The developers (1973) reported that percolation rates could
be measured within 15 percent in laboratory tests. The accuracy
of the device depends upon control of the applied vacuum such that
the soil water suction at the top of the trough is precisely equal
to that in the ambient soil at the same depth outside the trough.
Such control is most readily achieved with coarse textured soils
in which hydraulic conductivity decreases rapidly with increasing
soil water suction. Such soils are not encountered at the study
sites in the Grand Valley. In these fine textured soils, the
leachate measured by the extractor is quite sensitive to applied
vacuum. Because of the high hydraulic conductivity at relatively
low soil water suction, the extractors are also readily influenced
by a water table near the extractor trough. For this reason, many
of the sites investigated by the chloride profile technique were
considered unsuitable for vacuum extractor installation. Results
from some of those extractors installed are suspect because of un-
expectedly high water tables resulting from nearby ditch seepage.
Nonweighing Lysimeters . As a part of the USBR studies, ARS
installed six nonweighing lysimeters under a centerpivot sprinkler
irrigation system. These lysimeters are fabricated of fiberglass
panels with ceramic tubes in the bottom to allow percolating water
to be drawn off. The boxes are l.5m square, 45cm deep, with the
bottom of the box at 90cm below the soil surface. Thus, assuming
water is removed to prevent buildup of a water tables and subsequent
leakage, these lysimeters should, when corrected for changes in water
storage, give an accurate estimate of deep percolation, However,
the fact that the nonweighing lysimeters were installed by excava-
tion and refilled with disturbed soil limits their usefulness for
-------
13
68 u n
©
C
Surface
Butyl Rubber Air Bag
SECTION
Metal Trough
If
Ceramic Candles
To Pressure
To Vaccuum
if..___Access Wall
Evacuated for
Installation,
then Backfilled
-
Jill
-J
Sample Bottle
EL E VAT I ON
Extractor Trough
] I
Air Bag
Soil
31511
8
Figure 1. SchematIc of vacuum extractor Installation
-------
14
c llecting samples for chemical analysis. Because excavation and
replacement of a soil may change its infiltration rate by several
orders or magnitude, these devices should not be used under gravity
irrigation where infiltration rate controls the water intake. Under
the sprinkler system, infiltration is controlled by the sprinkler
at a rate sufficiently low to prevent runoff.
Soil Chloride Profiles . The above described techniques require
a considerable amount of equipment and time for installation and
operation, thus are not particularly suited for large scale surveys
of current irrigation practice. A technique of estimating deep
percolation based on salt concentration below the root zone has
been used with apparent success in other areas, and was suggested
for evaluation as a survey technique by chemists at the U. S.
Salinity Laboratory, Riverside, California. The primary reason that
irrigated agriculture inevitably results in concentration of salt
is that the plants extract soil water while selectively excluding
from plant uptake practically all ions in the soil solution. As
the soil solution moves progressively deeper in the soil root zone,
more water is extracted and the salt concentration in the remaining
water increases. Because of the complex chemical reactions, this
increasing concentration may result In exchange of adsorbed cations,
precipitation of some salts and dissolution of others. Thus, most
ion species are in a rather dynamic environment. However, the
chloride Ion Is relatively unaffected by these reactions. Being
an anion, it is not adsorbed on the clay complex. Common Cl salts
are quite soluble in water, thus are not present in solid form in
irrigated soils. Thus, the concentration of Cl in the soil solu-
tion is a direct function of the Cl concentration In the irriga-
tion water and the fraction of that water_removed from the soil by
evapotranspiration (ET). Thus, if the Cl concentration of the
soil solution Is evaluated at a depth below which no further ET
occurs, the ratio of Cl In the irrigation water to Cl in the soil
solution Is the fraction of applied irrigation water leaving the
root zone as deep percolation (leaching fraction). Further, if
percolation can be construed to be sufficiently slow that short
term changes In water quality or leaching are damped at the depth
of sampling, the chloride concentration at that depth can be con-
strued to represent the long term average result of historic irri-
gation practice and, a onetime sampling program can be used to
characterize the leaching history of an area.
To evaluate this technique, numerous soil samples were collected
from each of 28 fields representing the major soil types in the
Grand Valley.
Evapotranspiratlon . The second parameter of the water balance
not readily measurable Is the evapotranspiration. Numerous tech-
niques have been developed to estimate ET, ranging from strictly
empirical approaches to correlation with pan evaporation and sophis-
ticated energy balance approaches. The technique used in this
study is a modification of the ARS Scheduling Program as presented
-------
15
by Jensen (1969) and Kincaid and Heerznann (1974). This program
uses a modified energy balance technique in which solar radiation,
average temperature, dew point temperature and daily wind run are
used to estimate the net energy available for evapotranspiration.
Portions of this program related to estimation of net solar radia-
tion, soil heat flux, and vapor transport are empirically derived,
and it was desirable to check these calibration equations for the
Grand Valley area. The energy balance portion of the model calcul-
ates the potential evapotranspiration, that is the ET from a well
watered crop having a full cover. Therefore, a lysimeter was in-
stalled in an established alfalfa field to check the potential ET
calculations. This lysimeter was filled with a monolith of estab
lished alfalfa to avoid excessive delay in establishment of a per-
manent stand in the lysimeter.
Following calculation of potential ET, the ARS Scheduling
Program applies a stage of growth curve for each crop type to
calculate actual ET. The lysimeter previously installed for the
USBR study was under the sprinkler system where the corn is irri-
gated as often as four times daily. Thus it was desired to check
the crop coefficients under more conventional irrigation practice.
Three additional lysimeters were installed in furrow irrigated fields
planted to both corn and sugar beets.
The four lysimeters installed were of the hydraulic type des-
cribed by Hanks and Shawcroft (1965). The principle of operation
is illustrated in Figure 2. The inner box, in which the plants are
grown, rests on two pillows fabricated from reinforced butyl rubber
pipe. These pillows, filled with ethylene glycol solution, transmit
the fluid pressure resulting from the weight of the lysimeter to
a manometer where pressure changes can be read as a function of
time. To minimize problems of temperature effects on fluid density
and to reduce manometer height necessary, a portion of the pressure,
representing the bulk of the lysimeter weight, was tared by insert-
ing a mercury column in the manometer line. This taring device is
so designed that the readout manometer can be installed in a pit
below the soil surface, yet retain the sensitivity of a water mano-
meter. The sensitivity of the system is approximately 5mm manometer
change for each mm change in soil water.
Water Analyses
In conjunction with measurements of the various components of
the water balance, periodic samples of each of these components
were collected for laboratory analyses of water quality.
Sediment Concentration . Since rather large volumes of tail
water runoff characterize current irrigation practice in the Grand
Valley, it was suspected that sediment concentration would serve
as a direct indicator of the presence of runoff in return flows.
Therefore, sediment concentrations were determined gravimetrically
for both applied Irrigation water and tallwater runoff. A total
-------
Figure 2. Operational diagram of hydraulic lysimeter
Flexible
Membrane
Temperature
Compensation
Lysimeter Readout
Tare Pots
-I
0
-------
17
of 81 samples of irrigation and runoff water were collected for
sediment ana1ysi , in addition to periodic samples from the Govern-
ment Highilne Canal and the Colorado River at Grand Junction.
Chemical Analyses , Literally thousands of individual chemical
analyses have been run on soil and water samples collected during
the course of this study. The analyses were conducted in ARS lab-
oratories at Grand Junction and Fort Collins, with those collected
in conjunction with IJSBR studies conducted by the U. S. Salinity
Laboratory in Riverside, California. Specific analyses conducted
on the various samples are given in Table 1.
-------
Table 1. Chemical analyses conducted on various samples.
Ion
Sample EC Ca Mg Na K P HCO 3 Cl SO 4 NO 3
Soils for chloride study X
Drainflow X X X X X X X X
Applied irrigation water X X X X X X X X X X
Tailwater runoff X X X X
Percolate samples X X X X X X X X X
(extractors)
Groundwater X X - X X X X X X X
(observation wells)
-------
SECTION VI
DESCRIPTION OF FIELD SITES
The Grand Valley of Colorado comprises some 56,000 acres of
irrigated land (SCS 1976 survey) along the Colorado River both dir-
ections from the confluence of the Gunnison and Colorado Rivers.
Irrigation apparently began about 1883. Early studies (Miller,
1916) indicate that both ground water and soil salinization had
become problems by about 1915. Ground water quality has apparently
deteriorated little since that time, but increased demands on the
water of the Colorado River have made the problem of saline return
flows increasingly important.
The irrigated areas of the Grand Valley overlie the Mancos
shale formation, from which most of the soils were derived. This
shale, of marine origin, is interspersed with lenses of crystalline
salts, which are readily dissolved when water contacts these lenses.
As the river migrated back and forth across the valley, it eroded
the underlying shale and subsequently filled the resulting channel
with cobble. The resulting aquifer has long been too saline for
agricultural or domestic use. Likewise, intermittent streams from
the desert and Book Cliffs to the north cut channels perpendicular
to the river. As a result, topography of the shale surface is very
complex, with shale outcropping frequently, especially in the north-
ern and western portions of the irrigated area. The intermittent
streams from the desert presently cross the irrigated area through
ravines, often 30 or more feet in depth. These ravines, along with
several manmade ditches, serve as drains, returning groundwater,
tailwater runoff, and canal spillage to the river.
The soils resulting from this complex geologic history are
quite variable. The 1955 soil survey (Knobel, et. al., 1955) for
the valley lists 73 soil series identified in the valley. Although
fields are generally small, the field representing a single soil
series is the exception. This fact, more than any other, limited
the selection of sites for this study. Table 2 lists the propor-
tionate extent of the major soil series of the valley, which comprise
Table 2. Approximate acreage and proportionate extent
of major soil series in the Grand Valley
Series
Acres
Percent of Total
Billings
36000
29.5
Ravola
18900
15.6
ChipetaPersayo
18800
15.3
Fruita
13500
11.1
Mesa (Mack)
8400
6.5
Hinman
3100
2.5
19
-------
20
approximately 80 percent of the irrigated area. The studies report-
ed in this paper have involved farmer cooperation at 28 different
locations. Table 3 lists the site designation used in subsequent
discussion, along with the location and soil series.
Intensive Study
As mentioned earlier, initial ARS studies related to the
current problem were begun in 1973 with the cooperation of the
Bureau of Reclamation. A primary purpose of that study was to test
recently developed theories of minimum leaching. To attain this
goal, it was necessary to select a site having minimum potential
for a high water table. With the assistance of local Soil Conser-
vation Service personnel, the Ravola series was selected as best
representative of well drained soils in the valley. Final selec-
tion of the site at 20 1/2 and N Roads was based on relative uni-
formity of the soil, uniform soil slope, and the interest of the
cooperating farmer.
Soil samples were collected immediately upon selection of the
site, and a modified centerpivot sprinkler was subsequently in-
stalled on a portion of the field. The sprinkler controls were
rebuilt to provide water treatments to six sectors of the circle,
two replicates of each of three water treatments. It was intended
to apply 0, 5, and 15 percent leaching fraction to these plots.
Vacuum extractors, nonweighing lysimeters, soil salinity sensors,
and recording rain gauges Were installed in each of the sectors.
A large weighing lysimeter was installed in one plot.
The remainder of the field has been operated under gravity
irrigation, with vacuum extractors and salinity sensors used to
monitor the results. Water measuring devices were installed to
measufe both inflow and outflow from each of the four test plots.
The experimental layout is illustrated in Figure 3.
The intensive study site lies some 300 m down slope from the
Government Highline Canal, and drains into Little Salt Wash, which
runs immediately to the southeast. The area has been cropped ex-
clusively to corn since the study began. Virtually every onfarm
measurement (i.e., excluding canal seepage and drain flow studies)
conducted at other ARS sites in the valley has also been made at
this intensive study site.
Soil Chloride Profiles
Because the soil chloride profile technique promised a rapid
survey to estimate historic leaching fraction, the technique was
used to help locate suitable sites for other desired instrumentation.
Samples for chloride analyses were collected at 28 different loca-
tions throughout the valley, as illustrated in Figure 4. Sampled
fields represented each of the major soil series, and attempts were
made to sample fields both where drainage was expected to be good
-------
Table 3. Site Locations
Designation Name Address Soil
BR Bray 14.5 & 0.5 Billings sitcl & Ravola vfsl
CHR Christian 2936 B 1/2 Rd Hinman ci
CSUB CSU Beets 19 & L Ravola
CSUC CSU Corn 19 & L Ravola
CSUW CSU West 19 & L ChipetaPersayo
DP D. Phillips 59431.5 Ravola
EB Ed Bernal 16 & Q Ravola loam
EMA E. Mabie 2146 M Ravola
EMIJ E. Muth 12 & 0.5 Fruita ci
FKW Furakawa 2968 B Rd Hininan ci
FOR Forster 19 & H.5 Billings sitc
G 2225 E. L. Barbee 20 1/2 & N Ravola loam
GIE Gieske 14 & L.6 Fruita ci
HTM Hartman 10 & Q Mack (Mesa) clay
IN Indergaard 16 & P Billings sltcl
JB Jim Bernal 16 & Q Ravola loam
JS1 J. Studebaker 2198 I Billings
JS2 J. Studebaker 25 & G Ravola vfsi
KB K. Buniger 14.5 & P Billings ci
LDS LDS Church Farm 20 & N Ravola vfsl
LF L. Foraker 64331 Ravola
LS L. Sonunerville 21 & K Rd Billings sitci
PK P. Kelleher 43732 Billings
RL1 R. Larson 20431.3 Mesa clay
RL2 R. Larson 293lB.5 Hinman ci
RTG Rettig 31.8 & C Mesa ci
S 16 E. L. Barbee 20 1/2 & N Ravola loam
SM Smith 124921 Rd Ravola vfsl
SN Snodgrass 14.5 & Q Ravola vfsl
STS States 11.8 & P Fruita ci
-------
I
Salinity Sensor
o Plonweighing Lysimeter
Vacuum Extractor
D Weighing Lysimeter
1..)
Figure 3. Sketch of experimental field plots and instrumentation at intensive study site
-------
Figure 4. Location of fields sampled for chloride analysis
F..)
-------
24
and where high water tables were anticipated. Sampling was,
however, restricted to fields where only one (or in some cases,
two very similar) soil series was represented. Because preliminary
results from the intensive study area appeared to contradict the
earlier results of Skogerboe, et. al. (1972, 1974), several fields
east of Grand Junction, including Skogerboes study area, were
sampled by the chloride profile technique to determine whether per-
colation rates differ as greatly as the two studies suggested.
Direct Measurement of Deep Percolation
Following analysis of the soil chloride profiles, site selec-
tion for installation of vacuum extractors proceeded. Vacuum
extractors were not installed in the eastern half of the valley
because 1) Skogerboes (1972, 1974) studies were quite intensive
in that area, 2) water tables in that area are generally high,
precluding the use of extractors, 3) limited labor, and 4) prelim-
inary evaluation of chloride profiles indicated that percolation
in the eastern valley is indeed higher (as reported by Skogerboe)
than in the western valley. The requirement that water tables be
significantly below the root zone and that electrical power be
reasonably available limited the number of suitable sites.
In addition to the intensive study site, vacuum extractors
were installed on five farms representing the Billings, Ravola, and
Fruita soil series (see Figure 5). Subsequent high water tables
did cause problems in some areas as will be discussed in a later
section.
Measurements of Irrigation Application and Runoff
Again utilizing soil chloride analyses as a guide, but not
restricting sites to those apparently well drained, 27 locations
on 15 farms were instrumented to measure irrigation application
and taliwater runoff. As shown in Table 4, these farms represent
all the major soil series discussed earlier. Typical of most
irrigated land in the valley, the topography at all sites is quite
flat, with the slope of only one field (CStJW) exceeding 1.5 percent.
Eight of these fields (all except diR, CSUC, CSUW, RTG, GIE, FOR
and SM) were provided with access tubes to allow periodic soil
water measurement with neutron attenuation equipment. Again, no
attempt was made to evaluate inflowoutflow in the area of Skogerboes
earlier studies. As shown in Figure 6, these measurements were
confined to the western end of the valley, except for three sites
on Orchard Mesa south of the Colorado River.
Evapo transpiration
To compute a water balance for each field, the ARS Irrigation
Scheduling Program was used to simulate ET at each of the inflow
outf low study areas. Because of the proximity of evapotranspiration
-------
1 10 1W
I - f l
Figure 5. Location of vacuum extractors
-------
26
Table 4. Irrigation application and tailwater runoff
studies.
Site
Soil Type
Slope
1975 crop
EB
Ravola ci
.015
Barley
CRR
Hinman ci
.0047
Corn
CSUB
Ravola vfsi
.0053
Beets
CSUC
Ravola ci
.0065
Corn
CSUW
ChipetaPersayo
sd
.0168
Grass
FOR
Billings sltci
Corn
FKW
Hinman ci
.0059
Corn
C 2225
Ravoia 1
.014
Corn
GIE
Fruits cl
Corn
liT)!
Mack (Mesa) ci
.010
Corn
LDS
Ravola vfsi
.0065
Corn
LS
Billings sd
.0058
Corn
RTG
Mesa ci
-
Corn
SM
Ravola vfsl
.0079
Corn
STS
Fruita ci
.0080
Corn
-------
- - -- - - 1 NIOOW
4
Figure 6. Location of irrigation application and tailwater runoff studies
-------
28
study areas to the intensive study area, climatic data front that
area were used in all computer simulations. To minimize problems
of advective energy, the weather station was planted to a perennial
grass and irrigated by gravity methods to provide soil cover. The
weather station included a Class A evaporation pan, totalizing
anemometer, integrating pyranometer, standard and recording rain
gauges, and, in the standard Cotton Region shelter, a hygrothermo
graph and current, maximum and minimum thermometers.
An electronically weighing lysimeter (6 ft x 7.5 ft x 5 ft
deep) was installed as a part of the original study with the
Bureau of Reclamation. This lysimeter was installed under the
sprinkler (plot S2, 5% leaching). Because these plots were irri-
gated as often as four times daily, a practice unique to the research
plots, it was desired that ET be determined directly under conven-
tional furrow irrigation to refine the crop coefficient curves used
in the scheduling program. Thus, a weighing lysimeter was installed
and planted to corn in the furrow irrigated plots (G25) at the
intensive study site and two lysimeters, one planted to corn and
the other to beets, at the Colorado State University Experiment
Station near Fruita (CSUB, CSUC).
The potential ET, to which the above mentioned crop coefficient
curves are applied, is defined as the ET from a well irrigated crop
having a full canopy, such as alfalfa or grasses. An additional
lysimeter was installed at the CSU Station by filling the lysimeter
tank with a monolith taken from an established field of alfalfa.
This lysimeter served for recalibration of the potential ET calcu-
lations in the scheduling program. As the 1975 season progressed,
it became apparent that estimates of net radiation calculated from
total solar radiation measurements were in error. A Fritschen net
radiometer was ins tailed near the alfalfa lysimeter to provide
direct net radiation measurements and allow adjustment of that por-
tion of the program.
Lateral and Canal Seepage
At least four previous investigators, reported by Skogerboe
and Walker (1972), have attempted to conduct seepage measurements
on the delivery canals in the Grand Valley. ARSs interest in
conducting such studies as part of the current project arose from
the need to more accurately define the local hydrogeology in the
vicinity of the intensive study area. Results from the current
study are combined with those of previous investigators ii subse-
quent seepage analyses.
Two ponds were constructed immediately following the 1974
irrigation season by temporarily d iiim ng the Government Highline
Canal at 20 Road, Little Salt Wash and Adobe Wash (see Figure 7),
a total length of 17,800 feet. These two sections of canal were
underlain by alluvial material and weathered shale, respectively.
Seepage rates were monitored for seven days following ponding.
-------
Figure 7. Location of canal and lateral seepage studies
Current Seepage Studies
Skogerboe Seepage Studies
-------
30
To determine the relative importance of seepage from the smaller
laterals, a total of eleven ponds were constructed on three laterals
served by the Governmpnt Highline Canal in the fall of 1975 These
ponds, totaling 6100 feet in length, were on laterals 30, 33, and
35 cut through Ravola fine sandy loam overlying alluvium, Fruita
clay loam, and shale outcrops, respectively.
Earlier ARS measurements with seepage meters indicated decreas-
ing seepage rate as the irrigation season progresses. Further pond
ing tests were conducted in laterals 30 and 35 prior to the start
of the 1976 irrigation season. Four ponds, each 100 feet in length,
were constructed. Since diversion of river water down the canal was
impractical at this time of year, water was hauled by tank truck
from the Colorado River to fill these ponds for the spring seepage
tests.
Drain Flows and Ground Water
As a part of the current study, it was desired to attempt to
determine the route by which percolation and seepage return to the
river. During the winters of 197475 and 197576, flow measuring
flumes were installed in the major washes, as shown in Figure 8.
The first winter, flows were measured approximately weekly on Little
Salt, East and West Big Salt, Adobe and Persigo washes. During
the winter 197576, a total of 21 measuring stations were operated
on nine washes, Including the five above plus Hunter, Indian and
Lewis Washes and Leach Creek. Seven of these washes had more than
one flume installed. Samples were taken for chemical analysis at
each flume whenever the flow rate was determined.
The winter wash flows are quite small compared with normal
canal spillage or runoff from irrigation and summer thunderstorms,
requiring relatively small measuring flumes. Therefore, the flumes
could not be left in place during the irrigation season.
During the summer of 1974, a geologic study was conducted in
the vicinity of Little Salt and Adobe Washes. Electrical resistiv-
ity techniques and 23 drill holes were used to map the bedrock in
the area (Schneider, 1975). Most of the drill holes were fitted
with perforated plastic casing, through which groundwater levels
have been measured and samples collected periodically for chemical
analysis.
-------
Os
Wash Flow Studies
Geologic Investigation
Figure 8. Location of wash discharge studies and geologic investigation
-------
SECTION VII
RESULTS
Because the current study is quite closely related to ongoing
studies conducted for the Bureau of Reclamation, it is both diff I
cult and inappropriate to attempt to separate the results of the
two research programs. Therefore, where they add to the objectives
of this study, data collected from the USBR study will be used to
help satisfy the objectives of this study. Likewise, certain of
the data collected specifically under this study will be reported
to the USBR in support of that program.
As mentioned earlier, the surf icial geology of the Grand Valley
is quite complex, resulting in over 70 soil series classifications.
Even within a particular soil series, considerable soil variability
is encountered. Irregular bedrock topography, bedrock fractures,
clay layers and sand lenses are frequently encountered. As a re-
sult, high water tables, perched groundwater, artesian conditions
and substantial lateral flow may occur, especially during the irri-
gation season. Because of the many variables encountered, it is
impossible to precisely quantify the hydrologic parameters of the
valley as a whole. Efforts have been made to collect data from
farms covering a range of conditions, but results must be inter-
preted with full understanding of the statistical variability ex-
pected.
Chloride Sampling to Infer Leaching Fraction
Because chloride salts are quite soluble, the primary source
of chlorides in soils with a h i.s tory of leaching due to irrigation
is from the irrigation water itSelf. Figure 9 illustrates a typical
soil chloride profile under conditions of steady irrigation, evapo
transpiration and leaching. At the soil surface, the chloride con-
centration in the soil water is essentially that of the irrigation
water. The Cl concentration increases with depth as water is
extracted by the plant, until, below the root zone no further con-
centration occurs. Thus, the ratio of concentration in the irriga-
tion water to that below the root zone is equal to the fraction of
the applied irrigation water percolating below the root zone (i.e.
the leaching fraction).
Since water movement in partially saturated soils is quite
slow, it can be expected that the chloride concentration at 120 to
150 cm depth represents an integrated average leaching history for
several months or years previous to sampling. Thus, to properly
calculate the leaching fraction, one must use the average chloride
concentration of the water applied. Table 5 shows that the chloride
concentration of irrigation water delivered at the intensive study
site (G2225, Sl6) increases substantially as the season progresses.
Table 6 shows the mean concentration for the furrow plots at this
32
-------
33
CL Concentration
Figure 9.
Hypothetical Cl concentration profile of
soil solution under leaching conditions
0
Root
Zone
C)
C
0
0
a)
C)
0
I .-
C,
0
a)
0.
0
-------
34
Table 5. Composition of irrigation water at intensive 8tudy site
EC Cl
Date meq, L
6/27173 0.35 0.7
7/31/73 0.63 2.1
8/14/73 0.72 2.6
9/20/73 1.08 4.7
6/5/74 0.35 0.8
6/18/74 0.44 1.2
6/20/74 0.35 0.9
7/3/74 0.49 1.5
7/17/74 0.75 2.8
7/31/74 0.82 3.0
8/12/74 0.90 3.9
8/29/74 1.08 4.9
6/18/75 0.34 1.0
7/10/75 0.36 0.8
7/25/75 0.52 1.5
8/5/75 0.69 2.1
8/11/75 0.78 3.0
8/25/75 0.91 3.7
9/2/75 0.95 4.2
9/15/75 1.09 4.9
9/22/75 1.02 4.5
10/7/75 1.03 5.1
-------
35
site for each of the three years of data available, weighted by the
depth of infiltration at each irrigation (i.e. at each Cl concen-
tration). Since the chloride profile technique is based on the
assumption that Cl concentration below the root zone is the result
of at least several months past irrigation history, it is reasonable
to assume that the analyses from a set of samples in the above
fields would change little over the three year period. If the Cl
concentration of these samples were 15 meq/1, then the indicated
leaching fraction would range between .127 and .202, depending on
the irrigation water analysis used for computations. The potential
error in using analyses from a single sample of irrigation water
is even greater. If the leaching fraction resulting in the same
]5 meq/l soil solution concentration were calculated from individual
Irrigation water analyses (Table 5), the apparent leaching fraction
would range from 0.053 to 0.340.
Table 6. Weighted chloride concentration in irrigation water.
Cl
Year
Plots
meq/l
1973
S16
G2225
2.13
2.36
1974
S16
G2225
3.03
2.30
1975
S16
G2225
1.97
1.90
Average
Sl6
G2225
2.38
2.19
To be theoretically correct, application of the method should
take into account the water applied by precipitation, as well. The
average annual precipitation in the Grand Valley is 21 cm (Skogerboe,
et. al., 1974), distributed approximately uniformly through the
year. If one assumes that half the winter precipitation (12.5 cm)
evaporates, and that the summer precipitation reduces the Irrigation
needed to meet the total year round average ET of 91.5 cm, the
weighted average Cl shown in Table 6 would be reduced from 2.19 to
1.77 meq/1. For the same soil solution concentration of the pre-
vious example (15 meq/1) the calculated leaching fraction is 0.146
when irrigation water concentration alone is used, 0.118 when the
effect of precipitation is included.
One factor further complicating application of the chloride
sampling technique in the Grand Valley is the observation (to be
discussed in a later section) that the infiltration rate of most
soils in the valley is two to three times greater during the first
-------
36
irrigation of the season than during subsequent irrigations. This,
combined with the practice of extended irrigation to sub across
for germination, undoubtedly results in relatively high deep percol-
ation during the first irrigation. Since the Cl concentration is
quite low at this time, and since the soils of the valley are
characterized by deep cracking allowing rapid percolation, it is
possible that this early irrigation results in a flushing of Cl
from the lower profile resulting in an unexpectedly low Cl concen-
tration.
These factors, which complicate calculation of leaching frac-
tion from soil chloride profiles, tend to reduce the chloride con-
centration below the root zone below that expected from analysis
of the irrigation water. As a result, estimates of leaching frac-
tion are higher than the actual leaching fraction. Perhaps from
this standpoint alone, the method is a useful tool in that it gives
an upper limit to estimates of deep percolation. With these points
in mind, we proceed to analyze the results of the current chloride
profile studJ es.
More than 1500 individual soil samples were analyzed for Cl
concentration in a 1:1 soil solution extract. To calculate leach-
ing fraction, it is necessary to convert these concentrations to
the concentration at which water is mobile under gravitational
forces. Results of soil water characteristic determinations at
the intensive study site indicate that the water content at field
capacity (1/3 bar suction) is about 20% 2 a dry weight basis.
This figure was used to normalize all Cl data collected. Use of
a single water content to normalize all samples undoubtedly shifts
the normalized values for a particular site somewhat. However, the
overall error introduced by using the common factor is minimal,
since all soils (except on Orchard Mesa) are quite fine textured.
The soils at the intensive study site, for which the 20% field
capacity was determined, are intermediate to the texture of the
other soils studied. Table 7 shows the average Cl concentration
as a function,of depth. Each value shown is the average of all
samples collected at a particular sampling time. Leaching fraction
calculations for all samples were based on the three year average
Cl concentration of irrigation water at sites G2225 (Table 6)
corrected for the average annual precipitation as shown in the pre-
vious example. Weighted Cl concentration of applied water was
calculated to be 1.77 meq/1. Nineteen of the 71 profiles, sampled
show an inverted chloride profile (indicated by asterisk) i.e.,
higher Cl concentration at the surface, decreasing with depth.
Such a profile is presumed indicative of a net upward flow of water
from the water table, and eventually results in salinization of the
soil. No production history is available for these sites to deter
mine whether, in fact, salinization is occurring. A calculated
leaching fraction has been shown for all profiles, although if these
inverted profiles are truly indicative of net upward flo , the leach
ing fraction is zero, and Cl concentration is indicative of ground-
water quality.
-------
Table 7. Chloride concentrations at 20Z (dwb) soil water content
Cl,
meq/9.
Indicated
leaching
Site Soil type Date No. Samples 030 3061 6191 91122
122152 fraction
BR
CHR
CHR
I
II
Billings sitci
Hinman ci
unman ci
Hinman ci
Hinman ci
Hininan ci
4/74
6/17/75
7/8/75
9/18/75
6/17/75
7/8/75
30
12
12
15
12
12
38.15
1.02
.95
4.24
3.35
1.36
17.48
1.55
1.16
3.47
5.28
3.65
10.23
1.70
1.26
4.12
3.27
4.23
11.91
2.69
1.42
3.43
3.30
4.49
5.45
3.79
*0.32
0.66(a)
1.25(a)
0.47(a)
0.54
0.39
CSUB
CSUW
DP
ER
EMA
EMU
Ravola vfsl
Ravola vfsi
ChipetaPersayo
ChipetaPersayo
Ravola
Ravola loam
Ravoia
Fruita ci
6/3/75
11/3/75
6/23/75
6/30/75
12/74
4/74
12/74
4/74
15
15
12
12
19
40
48
44
2.89
8/15
4.06
3.97
6.60
5.16
6.15
9.88
5.18
3.09
3.91
2.13
5.94
13.97
4.54
6.81
6.65
4.96
4.04
2.19
9.61
11.98
3.81
5.86
13.93
4.91
5.09
2.65
10.74
8.54
2.49
5.97
17.27
8.54
6.89
6.74
2.54
4.79
0.10(a)
0.21(a)
0.35(a)
0.67(a)
0.26
*0.26
*0.70
*0.37
FKW
FKW
FKW
I
II
III
Hinman ci
Hininan ci
Hinman ci
Hinman ci
Hinnian ci
Hinman ci
Human ci
6/17/75
6/24/75
6/13/75
6/24/75
9/18/75
6/24/75
9/18/75
12
12
12
12
13
12
13
4.80
4.79
4.68
2.91
5.27
7.25
6.10
6.19
4.21
5.31
4.29
9.65
7.42
6.65
5.12
5.53
5.38
4.69
5.95
7.61
6.59
6.23
4.06
5.81
4.54
4.29
7.96
3.03
2.78
2.96
0.28(a)
0.44(a)
0.30
0.39
*0.64
0.22
*0.60
G22
G23
G24
G25
Ravoia loam
Ravoia loam
Ravola loam
Ravoia loam
Ravoia loam
Ravoia loam
Ravoia loam
Ravola loam
12/74
8/18/75
12/74
8/18/75
12/74
8/18/75
12/74
8/18/75
5
29
5
30
15
57
15
60
10.30
2.80
3.87
5.16
2.63
3.32
3.62
5.31
7.81
2.20
3.66
2.51
5.21
2.15
3.59
5.84
8.12
2.62
4.28
1.45
6.26
2.60
4.91
6.72
17.82
2.61
3.13
1.49
7.28
3.24
9.79
7.57
13.99
2.24
0.58
1.72
8.85
3.63
777
8.15
0.13
0.79
*3.05
*1.03
0.20(a)
0.49(a)
0.23
0.22
-------
Table 7. Chloride concentrations at 20% (dwb) soil water content
Page 2
Cl , meq/&
Indicated
leaching
Site Soil type Date No. Samples 030 3061 6191 91122
122152 fraction
HTM Mack(Mesa) clay 6/24/75 12 2.83 7.29 5.99 4.11 0.43
Mack(Mesa) clay 9/12/75 15 3.64 3.82 3.90 4.02 3.57 0.50
IN Billings sitci 4/74 18 23.15 11.49 8.72 6.55 8.30 *0.21
JB Ravola loam 4/74 45 8.90 9.53 9.19 10.61 10.24 0.17
JS1 Billings 12/74 50 8.44 35.92 60.30 103.05 79.15 0.02
JS2 Ravola vfsi 12/74 40 19.56 19.93 26.39 35.58 34.10 0.05
KB Billings ci 4/74 45 11.23 7.29 9.36 10.89 12.79 0.14
LDS Ravola vfsi 12/74 47 7.35 11.67 17.07 18.57 17.53 0.10(a)
R.avoia vfsl 9/26/75 15 4.90 6.76 3.12 3.84 4.21 0.42(a)
LF Ravola 12/74 38 11.57 7.05 8.48 13.04 14.43 0.12
LS Billings sitcl 12/74 48 5.37 6.60 5.20 6.01 5.40 0.33
Billings sltcl 9/19/75 15 4.12 4.99 8.16 8.87 8.77 0.20
RL1 Mesa clay 12/74 21 3/47 3.79 4.80 3.95 7.65 0.23
RL2 Hintn n ci 12/74 46 5.98 7.47 6.67 5.53 6.26 0.28
RTG I Mesa cl 6/11/75 9 10.88 5.40 18.84 7.58 0.09
Mesa ci 6/16/75 12 7.33 9.57 6.92 8.10 0.22
RTG II Mesa ci 6/11/75 12 8.35 9.90 10.71 8.09 0.22(a)
Mesa ci 6/16/75 12 3.44 3.57 5.21- 4.68 0.38(a)
RTG III Mesa ci 9/12/75 15 4.33 5.54 3.62 4.90 2.76 0.64
Si Ravola loam 12/74 15 2.08 6.58 6.32 11.64 8.91 0.20
Ravola loam 8/13/75 25 3.71 3.43 6.54 6.60 6.49 0.27
$2 Ravola loam 12/74 15 2.64 6.78 10.14 15.14 12.09 0.15
Ravola loam 8/13/75 25 5.24 5.38 8.24 10.89 12.91 0.14
$3 Ravola loam 12/74 15 2.77 7.33 7.71 8.35 9.33 0.19(a)
Ravola loam 8/13/75 25 3.40 3.08 3.07 4.56 4.82 0.37(a)
S4 Ravo].a loam 12/74 15 2.95 6.30 6.53 8.15 12.56 0.14(a)
Ravola loam 8/13/75 24 3.52 4.27 5.97 7.97 4.22 0.42(a)
S5 Ravola loam 12/74 15 2.67 6.52 9.14 12.44 11.34 0.16
Ravola loam 8/13/75 25 3.17 4.80 8.72 10.87 8.43 0.21
S6 Ravola loam 12/74 15 2.03 5.64 8.59 13.54 16.58 0.11
Ravola lσΰm 8/r3/75 21 3.62 3.42 - 3.11 6.03 - 10.93 0.16
-------
Table 7. Chloride concentrations at 207 (dwb) soil water content
Page 3
Site
Soil type
Date
No.
Samples
030
3061
Cl , meq/R.
6191
91122
122152
Indicated
leaching
fraction
SM
Ravola vfsl
6/16/75
11
32.23
13.99
11.85
13.17
*0.13
SN
Ravola vfsl
4/74
10
31.45
9.50
11.53
4.40
4.60
*0.38
STS I
Fruita ci
6/10/75
12
7.25
5.70
3.28
4.81
*0.37
Fruita ci
6/13/75
12
5.67
5.04
4.89
3.47
*0.51
Fruita ci
6/20/75
9
8.15
6.40
4.14
3.92
*0.45
Fruita ci
9/19/75
14
12.90
6.16
2.77
4.21
6.09
*0.29
STS II
Fruita ci
6/17/75
12
6.09
5.18
394
3.88
*0.46
Fruita ci
9/25/75
15
6.55
6.04
3.85
3.15
2.48
*0.71
STS III
Frulta ci
6/16/75
12
5.94
5.64
3.83
4.32
*0.41(a)
Fruita ci
6/25/75
12
7.66
4.40
4.03
2.74
*0.65 (a)
* Indicates inverted profile, indicative of net upward water flow
(a) LF from two sampling dates differ by more than one standard deviation
-------
40
At several sites, Cl samples were collected periodically to
test the assumption that Cl concentration below the root zone
responds only to long term changes in management. In some instances
(e.g. CSUW, FKW I, RTG II, STS III) leaching fractions calculated
from samples taken immediately before and immediately after a single
irrigation differed by more than their respective standard devia-
tions. Further sites showed significant changes within a year,
suggesting that the Cl concentration below the root zone is influ-
enced by short term events such as flows into surface cracks.
Few successive samplings showed close correspondence of cal-
culated leaching fractions (e.g., HR II, LS, RTG I), even though
the values did not show statistically significant differences. The
mean value of individual standard deviations of leaching fraction
exceeded 0.1, or about 1/3 of the mean leaching fraction (see
Table 8). The standard deviation of the mean was even greater at
0.22, indicating a high degree of variability within Individual
fields. Even greater variability was observed from field to field.
Detailed statistical analyses show that 47 soil profiles per field
would be needed to reduce standard deviations within an individual
field to within ± 10% of the calculated leaching fraction. To
characterize the entire valley would require sampling an estimated
104 fields, for a total of approximately 25,000 individual soil
samples. These numbers presume that no change in calculated leach-
ing fraction occurs with time, which is an unsubstantiated assumption
at this time.
From Table 8, one can observe apparent differences In the mean
leaching fraction calculated for different soil types, although
there is no statistical difference between these mean leaching frac-
tions. The relative magnitudes do correspond somewhat with measured
Table 8. Average leaching fraction as calculated
by chloride profile technique.
Soil type
Leaching Standard
fraction deviation
Remarks
Billings
hipetaPersayo
Fruita
Hinman
Mack(Nesa)
Ravola
All samples
0.206 0.134
0.223 0.118
0.510 0.226
0.469 0.136
0.475 0.287
0.497 0.268
0.339 0.181
0.231 0.157
0.361 0.536
0.308 0.217
0.388 0.392
(a)
(b)
(a)
(b)
(a)
(b)
(a)
(a)
(b)
(a)
(b)
(a) Includes only
normal chloride profiles
(b) Includes all samples analyzed, some or all
chloride profiles
inverted
-------
41
cumulative infiltration rates, which will be discussed later, with
Billings and Ravola soils having the least infiltration, Chipeta
Persayo, Hlnman, and Mesa soils having the highest infiltration
rate.
The chloride profile technique for calculation of leaching
fraction has apparently proven successful for other investigators,
particularly in the desert Southwest where precipitation is neg
ligible, irrigation is applied practically year around, and water
quality probably varies slowly because of reservoir impoundment or
pumping from groundwater aquifers. However, the usefulness of the
method in the Grand Valley is not obvious because the direct river
flows used for irrigation vary more than ten fold in Cl concentra-
tion over a season, annual precipitation is approximately 25% of
ET, and irrigation water is applied during only about 40% of each
year. Under such conditions, leaching fractions estimated by this
method likely represent an upper limit of actual leaching. Based
on this assumption, and assuming an average ET during the growing
season of 81 cm (32 inches), the maximum expected deep percolation
loss for the 56,000 irrigated acres is 66,400 acre feet annually.
The actual deep percolation is probably considerably less as will
be discussed subsequently.
Direct Measurement of Water Balance Components
Furrow Irrigation InflowOutflow Studies
To determine efficiency of furrow irrigation in the Valley, 27
fields on fifteen farms were instrumented to measure irrigation
water application, tailwater runoff, and, at selected sites, soil
water storage and deep percolation. Table 9 summarizes the instru-
mentation installed at each site, and the number of irrigations
studied during each growing season. During 1975, at least every
other irrigation was studied at each site. Continuing studies
during the 1976 growing season are included, particularly for the
first irrigation of the season, where analyses of results have been
completed.
During initial site selection, it was intended to obtain half
the cooperators from the group participating in the USBRs Irriga-
tion Management Services (INS). However, of higher priority was
the necessity to obtain sites in fields under a single soil type
and which were not expected to have high water table problems.
Further observations led to the conclusion that the present delivery
system and lack of water measurement devices for water delivery
would negate attempts to determine the effect of the current INS
on improved irrigation efficiency. Under the present conditions in
most of the valley, farmers could benefit from the time of irrigation
aspects of the service, but generally have no way to determine
accurately the net amount of application. Thus, final site selec-
tions were made without consideration of participation in the
irrigation scheduling services available.
-------
Table 9. Furrow irrigation studies, instrumentation summary
Field
Designation
Soil Type
Vacuum
Extractors
Neutron
- Tubes
Orifice
Box
Inflow
Flume
Runoff
Flume
No.
Sites
Number of
Irrigations Studied
1974 1975 1976
HTM
Mack(Mesa)cl
X
X
X
1
7
STS
Fruitaci
X
X
X
3
6
2
EB
Ravolaci
X
X
X
X
1
1
2
CSUW
Chipeta-Persayo
x
x
X
2
2
CSUB
Ravola
X
X
X
X
1
10
10
CSUC
Ravo la
X
X
1
1
LDS
Ravola vfsi
X
X
X
X
1
4
1
G2225
Ravola loam
X
X
X
X
X
4
42
16
12
SM
Ravola vfsl
1
1
LS
Bi liingsa itcl
X
X
X
X
2
6
6
CHR
Hintimncj.
*
x
x
1
5
FKW
Hinin n ci
X
X
X
3
9
5
RTG
Mesac l
*
3
8
GIE
Fruita ci
X
X
9
FOR
Billings sitci
X
X
4
TOTAL 160
*Individusi
furrow flumes used
F . .,
-------
43
Except for the G2225 plots and 1976 irrigation on the CSUB
plots, all sites were irrigated by the farmer himself at the same
time and rate of application as used on the remainder of the field.
Table 10 shows the pertinent flow data for all irrigations
studied. The average application time for irrigations studied was
27.7 hours, and bears little relation to either length of run or
stream size. The first irrigation, when required to obtain germin-
ation, is typically quite long to allow wetting to the top of the
seedbed. The average total application for all irrigations was 7.2
inches, with 33.6% of applied water leaving the field as taliwater
iunoff. Thus, the average net application was 4.8 inches. Net
applications were extremely high at the CHR and early Irrigation
at FKW sites, even though large stream sizes were used. Tailwater
runoff ranged from zero to in excess of 80% of applied water.
During the season, spot measurements of furrow cross section
and flow resistance were made. This was done by installing a small
flume at two or three locations in a furrow to determine the flow
rate and then measuring the width and depth of flow at several
points below the flume. The cross sections were considered rectang-
ular since the width was greater than five times the depth in all
cases. Table 11 lists hydraulic characteristics of several sites.
Computed surface storage varied between .1 and .2 inch during irri-
gation in most cases.
Intake rates for the different soil types were calculated from
the foregoing data and are listed in Table 12. Rates are expressed
In terms of the coefficients in the equation:
i = atb
where I is the cumulative intake, inches
t is intake opportunity time, hours.
The coefficients, a and b, are derived from a representative
cumulative intake rate curve, based on all monitored irrigations
of the soil in question.
Insufficient data were obtained on the Ravola clay loam soil
for intake analysis. Only two irrigations were obtained on the
Persayo soil. In general, the Billings, Ravola and Fruita soils
had similar intake characteristics and the variation between irri-
gations was greater than the variations between these soil types.
The Hinman and Mesa soils had generally higher intake characteristics,
however. Table 12 also contains values of cumulative intake at
12 and 24 hours, based on the average coefficients from 1975 and
1976 tests. Twelvehour intake for irrigations other than the first
varies only from 1.57 inches to 3.58 inches, except for the Hinmaxi
and Mesa soil, found east of the river on Orchard Mesa, which have
higher rates.
Analyses from early 1976 irrigations at 18 sites are shown in
Table 13. The 24 hour cumulative intake for the first Irrigation
-------
Table 10. Furrow irrigation studies
Run
Site Date L, ft
Stream
size
q, gpin
Slope
ft/ft
Appi.
T,
Time,
miii
Advance
Time, mm
Gross
Depth,
Appl.
inches
Meas. Runoff
inches
CHR I 5/21/75 1100 26.13 0.0047 1404 840 21.4 0.6
6/24/75 23.22 1410 600 19.1 0.6
7/21/75 16.84 1842 480 18.1 2.1
8/12/75 19.37 1230 270 13.9 2.6
8/29/75 12.53 1368 240 10.0 1.5
CSUB 6/19/75 710 2.21 0.0053 1440 165 3.5 2.1
7/3/75 4.40 1086 225 54 3.3
7/22/75 4.02 1056 105 4.8 3.6
8/1/75 3.72 642 165 2.7 1.4
8/9/75 3.69 1536 105 6.4 4.2
8/19/75 3.80 1374 135 5.9 4.0
8/29/75 5.62 1182 135 7.5 5.9
9/11/75 3.86 1056 225 4.6 3.3
9/25/75 2.47 1506 195 4.2 2.6
10/7/75 2.95 510 105 1.7 0.9
CSUB I 5/5/76 710 7.20 0.0053 1350 600 8.8 2.2
6/3/76 6.66 1320 120 8.0 3.6
CSUB II 5/5/76 710 10.30 0.0053 1260 300 5.9 1.5
6/4/76 5.92 2850 120 7.6 4.8
CSUB III 5/6/76 720 8.08 0.0053 1440 360 5.2 1.8
6/6/76 8.98 1470 120 5.9 3.8
CSUB IV 5/19/76 730 2.53 0.0053 2430 1020 5.4 1.0
6/7/76 9.61 1410 120 6.0 4.4
-------
Table 10. Furrow irrigation studies
Page 2
Run
Site Date L, ft
Stream
size
q, gpm
Slope
ft/ft
Appl.
T,
Time,
mm
Advance
Time, mm
Gross
Depth,
Appi.
inches
Meas. Runoff
inches
CSUB V 5/7/76 730 7.20 0.0053 1230 600 7.8 1.1
6/8/76 9.71 1440 120 6.2 4.0
CSUC 5/22/75 1120 7.75 0.0065 1374 270 6.1 2.9
CSUW I 6/23/75 500 733* 0.0168 1506 330 17.7 6.1
CSUW II 10116/75 500 3.76 0.0168 1260 60 7.6 6.4
EB 6/13/75 900 7.11* 0.015 1440 75 7.3 4.9
4/18/76 7.76 5670 105 19.6 12.1
6/9/76 12.80 1380 134 7.9 1.5
FOR 4/14/76 1280 14.36 1380 940 9.9 .4 U
5/25/76 14.15 1470 885 10.4 1.2
6/17/76 10.86 1440 1000 7.8 1.1
6/28/76 12.45 1380 820 8.6 1.3
FKW I 6/18/75 1280 15.33 0.0059 1470 225 11.3 4.1
4/16/76 16.42 0.0059 1830 760 21.9 1.9
6/5/76 19.22 690 81 4.8 .7
6/18/76 23.51 690 90 5.9 1.8
7/2/76 16.62 780 78 9.5 7.8
7/16/76 12.72 1320 104 6.1 1.3
FKW II 6/20/75 1280 10.45 0.0059 1260 270 6.6 2.2
7/13/75 6.23 1536 1170 4.8 .7
7/31/75 14.97 1506 270 11.3 6.6
8/19/75 8.89 1122 345 5.0 1.3
9/1/75 8.00 798 345 3.2 .2
-------
Table 10. Furrow irrigation studies
Page 3
Run
Site Date L, ft
Stream
size
q, gpm
Slope
ft/ft
Appi.
T,
Time,
mm
Advance
Time, mm
Gross
Depth,
Appl.
inches
Neas. Runoff
inches
FKW III 6/27/75 810 13.61 0.0060 1410 210 15.2 8.1
8/9/75 10.44 834 255 6.9 1.5
9/4/75 7.01 702 135 3.9 1.0
G22 7/1/75 600 5.00 0.013 1218 105 6.5 4.8
8/27/75 3.00 1566 345 5.0 1.2
9/11/75 3.60 1698 330 6.6 2.3
5/19/76 4.10 2790 120 12.2 2.0
6/16/76 4.36 1470 120 3.4 1.1
6/24/76 4.62 2520 240 6.2 .8
C23 7/2/75 600 4.40 0.013 1248 225 5.8 3.0
8/12/75 3.60 1632 210 6.3 3.6
8/26/75 3.20 1470 195 5.1 2.6 a
9/12/75 3.50 1566 360 5.8 1.9
5/17/76 4.90 2430 360 12.7 1.5
6/17/76 5.41 1350 60 3.9 1.3
6/26/76 6.37 1470 120 5.0 1.3
G-24 6/12/75 1200 5.60 0.014 1074 495 3.2 .5
7/14/75 5.00 1470 420 3.9 1.4
7/29/75 5.10 1440 435 3.9 1.3
8/27/75 5.10 1458 480 4.0 .6
9/11/75 5.50 1662 465 4.9 1.2
5/19/76 7.05 2910 120 11.0 1.0
6/16/76 8.81 1470 120 3.5 1.3
6/24/76 9.02 2550 180 6.2 1.3
-------
Table 10. Furrow irrigation studies
Page 4
Run
Site Date L, ft
Stream
size
q, gpm
Slope
ft/ft
Appi.
T,
Time,
mm
Advance
Time, mm
Gross
Depth,
Appi.
inches
Meas. Runoff
inches
G25 6/13/75 1200 6.00 0.011 834 165 2.7 1.0
8/12/75 4.70 1584 435 4.0 1.6
8/26/75 5.00 1554 255 4.2 - 1.9
9/12/75 4.90 1566 450 4.1 1.1
5/17176 6.50 2490 480 8.7 1.0
6/17/76 8.83 1350 120 3.2 1.4
6/26/76 10.11 1470 120 4.0 1.5
GIE I 4/25/76 900 8.05 3300 2075 11.8 .1
5/16/76 6.80 1560 285 4.7 .4
6/9/76 7.07 660 180 2.1 .2
6/22/76 7.07 690 160 2.2 .9
GIE II 4/22/76 1260 14.29 2700 280 12.3 1.3
5/18/76 15.77 1170 225 5.9 .5
6/9/76 8.12 630 310 1.6 .1
6/22/76 7.92 570 325 1.4 .1
7/2/76 6.10 1440 220 2.8 .5
HTM 6/2/75 1140 6.00 0.01 2754 1890 9.3 .1
7/7/75 9.09 1602 135 8.2 3.4
7/19/75 9.60 1536 360 8.3 1.9
7/30/75 8.99 1758 315 8.9 2.5
8/5/75 5.20 1470 4.3 0
8/21/75 9.18 1470 225 7.6 4.5
9/3/75 9.07 1410 135 7.2 5.1
-------
Table 10. Furrow irrigation studies
Page 5
Run
Site Date L, ft
Stream
size
q, gpm
Slope
ft/ft
Appi;
T,
Time,
mitt
Advance
Time, mitt
Gross
Depth,
Appi.
inches
Meas. Runoff
inches
LDS 6/5/75 1200 8.31 0.0065 1440 270 6.4 3.2
713/75 7.85 2430 1080 10.2 1.6
7/26/75 5.99 3966 3180 12.7 .2
8/20/75 8.40 1470 750 6.6 .2
5/22/76 9.04 3660 2255 8.9 .3
LS I 6/5/75 1250 3.84 0.0058 2688 1125 5.3 1.6
7/2/75 5.88 1920 765 5.8 1.4
7/21/75 8.75 1602 405 7.2 4.3
8/5/75 7.42 2784 735 10.6 8.1
8/26/75 6.83 2850 660 10.0 5.3
9/9/75 6.63 2850 525 9.7 3.8
4/28/76 5.52 1440 580 5.1 3.0
6/14/76 3.13 1350 360 1.4 .3
6/30/76 3.47 1020 75 1.1 .2
LS II 5/7/76 1160 14.14 1440 580 11.3 1.6
6/16/76 15.04 2220 220 9.2 3.1
7/6/76 12.13 2700 200 9.1 3.6
SM 6/9/75 1000 6.81 0.0079 1122 165 4.9 2.6
STS I 6/12/75 1300 0.0080 165 5.4
7/23/75 270 6.5
8/4/75 195 7.0
5/13/76 10.39 2940 160 9.4 2.1
6/22/76 12.74 660 100 2.6 .6
STS II 6/14/75 1300 4.4
*Compljted from Depth Applied assuming 30 in. row spacing.
-------
Table 11. Hydraulic characteristics of furrow flow at selected sites, 1975 average
Site
Length
Slope
Depth
Width
Area
q
v
Manning
n*
Surface
Storage
Width
Depth
ft
ft/ft
ft
ft
ft 2
cfs
ft/sec
in
G2225
1200
.0110
.042
.68
.029
.011
.38
.049
.139
17
LDS
1200
.0065
.071
.56
.040
.013
.33
.059
.192
8
STS
1200
.0080
.086
.55
.047
.030
.64
.037
.226
6
FKW
1280
.0056
.110
.85
.093
.046
.49
.049
.446
8
LS
1200
.0058
.064
.76
.049
.033
.66
.026
.235
13
*n values computed assuming a rectangular channel.
-------
50
Table 12. Measured intake rates, Grand Valley soils
1975 Tests
Cumulative Intake
1/ 1 12 hours, 24 hours,
Soil Type a b inches inches
Billings silty clay loam, B 0.74 0.49 2.50 3.51
Fruita clay loam, Fe 0.43 0.67 2.27 3.62
Hinman clay loam, H, 0 0.63 0.70 3.59 5.83
Mack clay loam, Ma 0.60 0.58 2.54 3.79
Mesa clay loam, Mc 1.27 0.68 6.88 11.02
ChipetaPersayo silty clay loam, b 0.81 0.57 3.34 4.96
Ravola very fine sandy loam, R 0.52 0.58 2.20 3.28
Ravola loam, Re 0.38 0.66 1.96 3.10
Coefficients for intake equation of the form I = at where I is
cumulative intake, inches and t is intake opportunity time, hours.
-------
51
Table 12. l4easured intake rates, Grand Valley soils
Page 2
1976 Tests
First Irrigation
Soil
Type
1/
a
Cumulative
Intake
12 hours,
inches
24 hours,
inches
Billings
2.52 0.34
5.82
7.35
Fruita
0.83 0.64
4.03
6.26
Hinman
3.23 0.56
12.96
19.09
Ravola
0.78 0.60
3.42
5.17
Subsequent
Irrigations
Billings
1.06 0.49
3.58
5.03
Fruita
0.32 0.78
2.22
3.81
Hinman
0.57 0.72
3.43
5.66
Ravola
0.21 0.82
1.57
2.77
2 - Coefficients for intake equation of the form I = atb where I is
cumulative intake, inches and t is intake opportunity time, hours.
-------
Table 13. Measured intake rates, Spring 1976
2 Cumulative Infiltration
Site Date a b r 12 hour 24 hour
EB 4/18/76 .167 .825 .995 1.30 2.29
CSUB I 5/18/76 1.292 .532 .996 4.84 7.00
6/3/76 .516 .695 1.000 2.90 4.70
CSUB II 5/5176 .691 .624 .999 3.26 5.02
6/4/76 .198 .676 .998 1.06 1.70
CSUB III 5/6/76 .706 .487 .997 2.37 3.32
6/6/76 .282 .625 .998 1.34 2.06
CSUB IV 5/19/76 .887 .447 .985 2.70 3.67
6/7/76 .187 .672 .996 .99 1.58
CSUB V 5/7/76 2.531 .313 .970 5.52 6.86
6/8/76 .251 .694 .991 1.41 2.28
FKW I 4/16/76 3.234 .559 .995 12.96 19.09
6/5/76 .533 .848 4.38 7.89
6/18/76 .682 .750 4.39 7.39
7/2/76 1.290 .150 1.87 2.08
7/16/76 .434 .787 .999 3.07 5.29
FOR 4/14/76 3.449 .349 .986 8.22 10.47
5/25/76 2.732 .412 .999 7.61 10.13
6/17/76 2.432 .346 .999 5.75 7.30
6/28/76 2.300 .407 .999 6.33 8.40
G 22 5/19/76 .346 .883 .999 3.10 5.72
6/16/76 .092 1.026 1.000 1.18 2.40
6/24/76 .203 .860 .992 1.73 3.13
-------
Table 13.
Measured intake rates, Spring 1976
Page 2
Cumulative
2
Site Date a b r 12 hour
Infiltration
24 hour
G23
5/17/76
6/17/76
6/26/76
.850
.200
.248
.697
.831
.846
.992
.999
1.000
4.80
1.58
2.03
7.78
2.80
3.65
G24
5/19/76
6/16/76
6/24/76
.247
.162
.155
.956
.820
.911
1.000
.999
.998
2.66
1.24
1.49
5.15
2.19
2.81
G25
5/17/76
5/17/76
6/17/76
6/17/76
6/26/76
6/26/76
64
4
33
2
34
2
rows
rows
rows
rows
rows
rows
.500
.447
.170
.190
.195
.374
.714
.700
.729
.702
.781
.474
.976
.970
.990
1.000
.998
.995
2.94
2.54
1.04
1.09
1.35
1.22
4.83
4.13
1.73
1.77
2.33
1.69
GIE
I
4/25/76
5/16/76
6/9/76
6/22/76
1.984
.397
.301
.229
.456
.739
.781
.722
.970
.998
6.16
2.49
2.10
1.38
8.46
4.16
3.60
2.27
GIE
II
4/22/76
5/18/76
6/9/76
7/2/76
.629
.613
.342
.199
.743
.743
.714
.803
.995
.998
.999
3.98
3.89
2.02
1.46
6.66
6.51
3.31
2.55
LDS
5/22/76
2.219
.324
.919
4.96
6.21
LS I
4/28/76
6/14/76
6/30/76
.925
.114
.046
.368
.730
1.011
.995
.999
.989
2.31
.70
.56
2.98
1.16
U i
L .3
-------
Table 13. Measured intake rates, Spring 1976
Page 3
Site
Date
a
b
2
r
Cumu
12
lative
hour
Inf
24
iltration
hour
LS
II
5/7/76
6/16/76
7/6176
3.119
.321
.260
.322
.806
.765
.968
.986
.978
6.94
2.38
1.74
8.61
4.16
2.95
STS
5/13/76
6/22/76
.206
.201
.906
.961
.998
1.95
2.20
3.65
4.27
U I
-------
55
at most sites was nearly twice that of subsequent irrigations.
Such a phenomena is probably realistic since several irrigators
reported this observation. The reasons for such a drastic reduc-
tion in intake following the first irrigation are still under study,
but probably relate to either winter freezethaw cycles or the
common practice of deep plowing to cover crop residue. Regardless
of the cause, the result is that the infiltration rate is high at
the time long irrigations are applied for germination. As a result,
a disproportionate percentage of deep percolation loss probably
occurs during the first Irrigation.
These data will be furnished to the Soil Conservation Service,
USDA, for use in developing a method of designing more efficient
furrow irrigation systems in the Grand Valley. One phenomena ob-
vious from the data is that advance time shows significant variations
from one irrigation to the next. These variations are not always
a function of changes in stream size. There is therefore further
indication that intake rates vary considerably from one irrigation
to the next. This phenomena is perhaps most evident on the Mesa
soils. Large changes in intake from one irrigation to another will
make efficient surface irrigation design quite difficult, unless
innovative methods for surface irrigation can be developed such
that the irrigation system, rather than the soil, controls irriga-
tion application.
Chemical quality of taliwater runoff will be discussed in a
later section of this report.
guantity and Quality of Measured Deep Percolation
Vacuum extractors were Installed under 12 sites in 7 fields
(Sl6 plus those shown in Table 9) for direct measurement of deep
percolation losses. In spite of careful attention to site selection,
two of the extractors were subjected to sufficiently high water
tables that the data are suspect, as shown in Table 14. Four add-
itional extractors had operational problems during part of the
season sufficient to invalidate the data for those extractors.
Data from the operable extractors were used to calculate the
leaching fraction at each site. Total Irrigation application was
calculated by adding measured deep percolation to ET estimated
from lysimeter data. No value of leaching fraction was calculated
from depth of percolate collected at site EB because this field
was cropped to barley, for which no ET estimates were made. Leach-
ing fractions calculated by this technique ranged from .03 to .14,
with a mean value at all extractor sites of .08, considerably less
than the 0.22 leaching fraction calculated for the same sites from
the chloride profile technique. Table 15 compares the leaching
fractions calculated by these two techniques and by three additional
techniques to be discussed subsequently.
Leaching fraction was also calculated from the Cl concentra-
tion of the leachate collected in the extractors. The weighted mean
chloride concentrations from vacuum extractors, shown In Table 16,
-------
Table 14. Deep percolation measured from vacuum extractors and
nonweighing lysimeters, 1975
May
June
July
August
September
October
November
Total
cm
cm
cm
cm
cm
cm
cm
cm
EB 1 4.39 0.19 1.61 6.19
2 1.61 0.14 1.87 0.77 4.82
3 2.00 0.25 1.70 1.68 5.63
CSUB 1 0.30 5.13 3.84 9.27
2 0.20 2.07 5.05 7.32
3 0.22 0.27 0.49
G24 1 0.06
2 0.47 2.31 1.41 4.19
3 0.21 0.04 0.09 0.34
UI
G25 1 0.17 0.03 0.02 0.22 a
2 1.81 0.31 0.35 2.39 0.03 4.89
3 0.78 0.12 0.06 0.96
LDS 1 2.78 0.55 0.11 0.02 3.46
2 4.11 4.20 4.57 1.29 14.17 --
3 2.64 2.62 1.89 7.15
LS 1 2.55 1.61 4.44 0.29 8.89
2 1.96 0.26 2.25
3 2.21 0.84 3.50 0.28 6.83
Si 0.60 1.09 0.72 0.27 0.15 2.83
S2 0.26 0.83 0.66 0.47 0.64 0.33 3.18
S3 0.06 1.72 1.84 1.45 1.94 1.69 8.71
-------
Table 14. Deep percolation measured from vacuum extractors and
nonweighing lysimeters, 1975
Page 2
Nay
June
July
August
September
October
November
Total
cm
cm
cm
cm
cm
cm
cm
cm
S4 0.05 1.86 0.37 0.07 0.20 2.56
S5 0.09 2.14 1.38 1.01 0.80 5.40
S6 0.36 1.70 1.92 1.24 3.23 1.69 10.14
Non-Weighing Lysimeters
Si 1.09 3.74 2.99 1.76 2.07 1.96 0.63 14.25
S2 0.31 0.69 1.67 1.44 2.29 2.39 0.62 9.41i,
S3 0.01 1.13 0.54 0.02 0.19 1.89
s4 0.07 0.04 0.15 0.01 0.88 2.19 0.61 3.95
S5 0.01 0.09 0.09 0.29 0.20 0.88 0.24 1.79 ,
S6 0.03 0.01 0.03 0.28 2.59 0.01 2.96-i U i
1 Inoperative during all or part of season; disregard data.
? JMay have been influenced by high water table; disregard data.
-------
Table 15. Comparison of leaching fraction calculated by various techniques
Site
EB
CSUB
G24
G25
LDS
LS
Si
s2
S3
S4
S5
S6
MEAN LF
5
x
MEAN (G&S Plots)
Cl
Profile
0.26
0.15
0.34
0.22
0.26
0.26
0.23
0.14
0.28
0.28
0.18
0.13
0.22
0 02
0.23
0.03
Cl
Vacuum Extractor
0.08
0.36
o .19
0.14
O .26
0.10
0.05
0 09
0.09
0.09
0.25
0.06
0.15
0.03
0.12
0.02
0.11
0.05
0.08
0.14
0.10
0.04
0.04
0.10
0.03
0.07
0.12
0.11
0.03
0.19
0.12
0 02*
0.05
0 02
0.03*
0.11
0103
0.05
0.10
0.06
0109
0.18
0.06
0.13
0.17
0.10
0.02
0.10
0.02
Water
Volume
Water Volume
Water
Vacuum
Extractor
NonWeighing Lysitneter
Balance
U I
S
x
*
Inoperable during part of the season; disregard results.
-------
59
EB
CSUB
G24
G25
LDS
LS
Si
S2
S3
S4
S5
S6
11.7
18.0
35.3
15.5
17.4
20.1
42.1
1975
21.3
5.0
9.3
15.0
6.7
17.1
31.0
24.4
23.3
21.0
7.2
20.5
Table 16. Weighted mean chloride
concentration of percolate
collected in vacuum extractors
Cl, meg/L
Site 1974
-------
60
were divided into the weighted mean Cl concentration of total
applied water, taken as 1.77 meq/l as in previous calculations
for the Cl profile technique. Individual chemical analyses of
these samples are shown in Table Ai of the Appendix. Leaching
fractions calculated by this method ranged from .05 to .36, with
a mean of 0.15. As might be expected, this mean leaching fraction
lies between the means calculated from extractor volume and from
Cl profile analysis, since the accuracy of this calculation is
effected by the_same limitations as the Cl profile technique and
the weighted Cl concentration is affected by errors in volumetric
measurement by the vacuum extractors.
For the S16 sites, LF was also calculated from water collected
in the nonweighing lysimeters, using the same water application
calculated for the LF determinations from water collected in the
vacuum extractors. Though the mean leaching fraction calculated
by this method does not appear beyond reason, individual values do
not necessarily follow the trend of either the intended percolation
or the actual water application. As of this time, no explanation
of the erratic results from the non-weighing lysimeters is apparent.
These results are disregarded in subsequent discussion.
At the intensive study site (G2425 and Sl6) both water app-
lication and runoff were measured for the entire 1975 season.
These data, combined with changes in soil water storage and estimates
of ET allowed calculation of the total water balance to evaluate
deep percolation losses, as shown in the last column of Table 15.
These calculations gave similar results to those from the vacuum
extractors, and the mean calculated leaching fractions were not
significantly different.
Because the Cl concentration from the vacuum extractors, the
water volume collected by the vacuum extractors, and the water
balance technique gave similar results at the intensive study site,
and neither technique can be shown more accurate than the others,
perhaps the best estimate of actual leaching is given by the mean
of all three methods. This mean LF is 0.10, only 42% of the value
calculated by the chloride profile technique at these same sites.
The factors tending to increase apparent leaching fraction, as
calculated by the chloride profile technique, such as high inf 1].
tration rates early in the season and approximately tenfold change
in irrigation water quality over the season, exist valley wide.
Thus, it is reasonable to assume that this same correction can be
applied to the Cl profile samples collected throughout th 9 valley.
The maximum estimated leaching fraction of 0.308 is reduced to 0.129,
reducing the estimated average valley-wide annual leaching to 15.2 cm
(6.0 inches) and the annual total deep percolation to 28,000 acre
feet from the Grand Valley. These figures seem much more reasonable
in the experience of the researchers involved, as it was observed
to be very difficult to infiltrate a sufficient amount of irrigation
water to replace the calculated depletion on the Ravola soils at
the intensive study site.
-------
61
Measurement of Evapotranspiration
Initial instrumentation at the intensive study site included
an electronic weighing lysimeter under the center pivot sprinkler
(plot S2). Because this lysimeter is irrigated lightly and fre-
quently, it could be argued that ET measurements from this lysimeter
are not representative of that from the typical Valley corn field.
Thus, four additional lysimeters were installed during the winter
of 197475 to check potential ET estimates as well as crop coeffic-
ient curves.
Potential ET was calculated using the technique of Kincaid
and Heermann (1974). Calculated values are compared with measured
ET from a well watered alfalfa crop to determine accuracy of the
calculated potential. The alfalfa was harvested twice during the
growing season thus greatly reducing the measured ET for a short
period until regrowth provided full ground cover. Thus, measured
values of ET before and after cutting were extrapolated through this
post harvest period to adjust measured ET to that of a continuously
growing alfalfa crop. Figure 10 shows the comparison of cumulative
ET from the alfalfa lysimeter with cumulative estimated potential
ET. During the period 6/14 through 10/8 the ET for the alfalfa
lysimeter was 36.33 inches. Calculated potential ET during the
same period was 28.54 inches, only 87.6% of measured potential.
This difference suggests either errors in measurement of climatic
data or in estimation of empirical coefficients of the energy bal-
ance equation. The pyranometer used for solar radiation measure-
ments was checked against a recently calibrated Eppley pyranometer
for a period of several days during late summer, 1975. The two
instruments recorded total incoming radiation within 2% of one
another, considered to be acceptable agreement.
As calibrated at both Kimberly, Idaho and Mitchell, Nebraska,
the ARS computer scheduling model estimates net solar radiation,
depending on maximum and minimum temperature, saturated vapor
pressure and solar position, at approximately 50 to 60% of total
incoming shortwave radiation (the latter is more readily measured
than net radiation, especially In remote locations). During the
latter part of the 1975 growing season and in 1976, a Fritschen
type net radiometer was installed over the alfalfa field to provide
a calibration of this aspect of the scheduling program. Comparison
of the two methods showed that mean net radiation in the Grand
Valley is 80% of total solar, or 46% greater than calculated using
the calibrations from Kimberly and Mitchell.
These results were also verified on the corn lysimeters. Dur-
ing the period 6/14 to 10/8 the G25 lyslineter measured 31.23 inches
ET compared with a calculated ET of 19.4 inches, or 61% greater
than calculated. Part of the explanation for this large difference
may be due to the fact that the program reduces estimated ET as the
soil dries following an irrigation, to compensate for reduced con-
sumption as plant water stress increases. This aspect of the program
is probably overly compensating for the soils of this area, perhaps
due to the widespread occurrence of shallow water tables and the
-------
62
Julian Day
1975
Comparison of estimated potential ET with
measured ET from alfalfa
35
30
25
Alfalfa
U)
a,
0
C
a
C
0
0
I-
0 .
U)
C
a
4-
0
0.
a
I
LU
Calculated
Potential
160 180 200 220 240 260
280
Figure 10.
-------
63
ability of the crop to use groundwater. It should also be pointed
out that the G25 calculated ET was based on the actual irrigation
timing and amount on plot G25. The lysimeter was kept well watered,
and was not necessarily irrigated with the same depth or schedule
as the remainder of the field.
During this same period, the S2 lysimeter measured 26.63
inches ET, or 18% greater than the calculated value. Early in the
season, calculated ET was considerably higher than measured, prob-
ably due to overestimation of evaporation from the frequently wetted
soil surface. From 7/1 through 10/8 measured and calculated ETs
were 23.65 and 18.11 inches respectively, thus measured ET was 31%
greater than calculated.
Figure 11 shows the crop coefficient curves calculated by
various methods. First, from the ratio of alfalfa ET to calculated
potential, it is apparent that the error in potential ET calculation
is not constant throughout the season, but peaks in mid season.
As expected, the crop coefficient curves calculated from estimated
potential indicate higher crop use than possible with the available
energy (i.e., the actual net available energy is greater than est-
imated by the scheduling program).
Crop coefficient curves calculated from potential ET as meas-
ured in the alfalfa are much more reasonable. Several points are
worthy of mention, however. First, it appears that peak water use
occurs later In the season than predicted by Kincaid and Heermann.
Second, the curves indicate higher ET early in the season from the
sprinkler irrigated corn than from the surface irrigated. During
this period, plant cover is sparse and the crop is able to utilize
only a portion of the net radiation energy for transpiration.
Because the soil surface is considerably wetter under the frequent
irrigation applied by the sprinkler, one would expect more evapo-
ration from the soil at this stage in S2 than in G25, where irriga-
tion is applied at about 14 day intervals. As full cover is reached,
however, and the crop is able to utilize most of the net radiation
energy for transpiration, the wetness of the soil surface is of
little importance. Following full cover, in fact, it appears that
the ET from the S2 plot is significantly less than from the gravity
irrigated plot. The water balance for the sprinkler lysimeter Is
based upon the amount of water, in liquid phase, actually applied
to the crop and soil surface (i.e., water that can be weighed by
the lysimeter). It Is obvious that part of the water pumped through
the sprinkler heads evaporates before it hits the crop canopy,
especially during periods when net radiation energy is high. From
Figure 11, it is seen that peak measured ET from the sprinkler ly
simeter is about 12% less than from the surface irrigation lysimeter.
Earlier data collected at this location showed that during the
afternoon in mid suimner, about 16% of the pumped water evaporated
before hitting the crop canopy. Many investigators consider this
evaporation to be a loss of water. The current data, however,
indicate that this airborne evaporation does in fact use part of
-------
1.6
1.4
.2
1.0
0
4-
C
4-
0
I-
U i
I.-
Ui
0.4
0.2
0
60 180 200 220 240
Julian Day, 1975
Alfalfa/CaIc. Potential
SZ Corn /Calc. Potential
625 Corn /Calc. Potential
S2 Corn/Alfalfa
625 Corn/Alfalfa
Published Crop Coefficient
Curve (Kincaid & Heerman, 1974)
320
0 .
260
Figure 11. Ratio of evapotranspiration to potential ET as a function of time
-------
65
the incoming energy (it must, of course) thus effectively reducing
the transpiration through the plant by approximately the same amount
as the airborne evaporation. Therefore, direct evaporation from
a sprinkler system cannot be considered a loss of water nor a re-
duction in irrigation efficiency.
Two additional lysitneters were installed on the Colorado State
University Experiment Station near Fruita. The first was installed
under corn and operated from 6/14 through 10/8/75. During this
period, measured ET was only 17.41 inches, only 55% of the ET
measured on the G25 lysiineter under the same type irrigation. Corn
plants on this CSUC lysimeter were observed to be stunted, indicat-
ing poor growing conditions; therefore these data were discounted
as unrepresentative.
The second lysimeter was planted to sugarbeets, with consider-
able difficulty encountered in establishing a stand. The crop was
finally established by transplanting on 7/12/75, and the lysimeter
performed satisfactorily until 8/19. At that time, overirrigation
of the adjacent field resulted in flooding of the readout well.
Despite diking, excess water moving through the backfill material
resulted in flooding the well at two subsequent irrigations, float-
ing it out of the ground the last time (9/22/75) rendering the ly
simeter useless. Total indicated ET during the period 7/12 through
9/22 was 20.59 inches compared with 23.02 inches for the G25 corn
lysimeter and 24.65 inches measured potential. Thus the gross
value of ET during this period is reasonable, but without much con-
fidence. From final planting (7/12) to first flooding (8/19),
total measured ET was 13.51 inches compared with 13.99 inches po-
tential. These figures are felt to be reasonably reliable, but
did not accomplish the original goal of verifying the crop coeffic-
ient curve for sugarbeets.
With the exception of the lysimeter that was flooded beyond
use, all lysimeters are being operated during the 1976 growing
3eason to strengthen ET estimating procedures.
Evaluation of Tailwater Runoff
Results of tailwater runoff measurements were briefly dis
cussed in connection with Table 10, where runoff depths are tabulated
for each irrigation measured. Table 17 summarizes the results of
these studies. It is apparent from Table 17 that a considerable
amount of tailwater runoff leaves the field, a fact easily verified
by field visits during the irrigation season.
The relatively low infiltration rates and slow capillary move-
ment of water in these soils necessitate long infiltration oppor-
tunity time to attain reasonable amounts of infiltration, especially
in the early spring when the farmer must rely on irrigation to wet
the seedbed for germination and emergence. Large amounts of runoff
are also indicated by the ratio of advance time to total time of
irrigation. The average irrigation time for the fields studied was
-------
Table 17. Tailwater runoff from study sites in Grand Valley
0
0
Soil
No.
Sites
No.
Irrigations
Fraction
of
Runoff
Mean
Standard Deviation
of Mean
Billings
2
16
.321
.052
chipetaPersayo
1
2
.593
.249
Fruita
2
15
.141
.034
unman
2
19
.255
.047
Mack
1
7
.319
.102
Ravola
9
58
.400
.028
Average all studies
. 336
Weighted mean
.363
- 1 Not representative;
uncropped area.
-------
67
27.7 hours, while the average irrigation flow reached the bottom
of the field in 6.6 hours. Such rapid advance contributes to a
high degree of uniformity in infiltration.
The data of Table 17, though limited in statistical signif 1
cance for some soils, shows that runoff percentage is not signif
icantly different from the Billings, ChipetaPersayo, Hinman and
Mack soils. Differences in management from farm to farm and even
from one irrigation to another are greater than soil differences.
It does appear, however, that less runoff than average occurs from
the Fruita soils, and more than average from the Ravola soils. Ex-
tensive data collected on Ravola soils give some idea of the reduc-
tion in runoff that can be achieved by careful water management.
From the farmer irrigated sites, average tailwater runoff was 47.6
percent of total applied irrigation water. However, at the inten-
sive study site, where net application was predetermined and appli-
cation and runoff monitored during irrigation, average runoff was
reduced to 31.8 percent, or one third less than on farmer irrigated
sites. This reduction in runoff, however, was accomplished at the
expense of a considerable amount of labor and expertise to monitor
application during the course of an irrigation. Such a practice
is certainly not feasible for the farmer operated system, and it
is not likely that substantial reductions in tailwater runoff can
be achieved on a valleywide basis until innovative irrigation
techniques, including automation and automatic water measurement
can be developed.
Even though amounts of tailwater runoff are relatively large,
the detrimental effects of salt loading from this runoff are not
Immediately obvious. During the 1975 irrigation season, water
samples were collected periodically at the various study sites for
both sediment and chemical analyses. The results of these analyses
are shown in Table 18. Note that there is no statistical differ-
ence in electrical conductivity, chloride concentration, or nitrate
concentration between the delivered irrigation water and tailwater
runoff. Since the ions involved are quite water soluble, they are
readily moved beneath the soil surface by the advancing irrigation
front and are not subject to significant removal from the soil by
surface runoff water.
Sediment concentration, however, is increased by a factor of
approximately ten as water moves through the field. Thus, the
average acre inch of runoff increases in sediment load by about
328 pounds. Based on an avezage crop ET estimate of 32 inches and
the deep percolation and runoff estimates derived in this study,
the 63 inches farm delivery and 8 inches precipitation reported by
Skogerboe (1972) can be apportioned as shown in Table 19. Using
these figures, the calculated sediment contribution is about 6560
pounds per acre or 190,000 tons total annually, assuming all tail
water runoff returns directly to the river. Such is not the case,
owever, as a portion of tailwater runoff is picked up downslope
-------
Table 18. Chemical and sediment analysis of irrigation water 1975
Site
Date
EC
nvnho/cm
Cl
meq/l
NO 3
meq/l
P
ppm
Sediment
gil
EC
mm ho/cm
Cl
meq/l
NO 3
meq/l
P
ppm
Sediment
gil
CHR
6/26
7/24
8/29
.610
.769
.880
1.57
.083
.124
.032
.001
0.23
0.22
0.36
.630
.768
.940
1.72
.077
.076
.029
.060
0.18
0.20
0.16
CSUB
6/19
7/23
8/19
.357
.557
.831
.574
1.46
2.66
.123
.041
.226
.006
0.07
0.20
0.05
.394
.535
.852
.666
1.28
2.32
.197
.035
.130
.590
.080
.090
0.34
CSUW
6/19
.461
.942
.105
.003
0.18
.471
.932
.101
.006
0.11
EB
8/29
.908
3.59
.309
0.03
.860
3.60
.150
.146
0.81
FKW I
FKW II
6/19
8/ ].
8/20
9/2
9/3
.583
1.24
1.26
.808
3.61
4.19
.075
.080
.150
.003
.007
0.14
0.20
0.07
0.01
0.01
.589
1.24
1.25
.833
3.59
4.25
.140
.105
.120
.034
.051
0.96
0.38
0.14
0.05
0.08
G22
G24
G25
9/11
9/11
6/13
8/27
.442
.934
.832
3.72
.068
.287
.002
0.12
0.25
0.10
.546
.937
.930
3.68
.150
.309
.258
0.13
20.5
2.44
6/3
6/30
7/31
.519
.410
.634
1.26
.736
1.84
.093
.062
.064
.097
0.27
0.14
0.08
.535
.440
.643
1.38
.756
2.08
.115
.086
2.96
.073
1.83
0.28
0.54
LDS
7/28
8/20
.905
1.81
3.54
.109
.142
.025
.001
0.11
0
-------
Table 18. Chemical and sediment analysis of irrigation water, 1975
Page 2
Site
Date
low_____________________
NO 3
meq/l
P
ppm
Sediment
g/l
EC
nvnho/cm
Cl
meq/l
N0 3
rneq/l
P
ppm
Sediment
g/l
EC
nvnho/cm
Cl
meq/l
LS 6/3 .487 1.12 .130 0.39 .515 1.11 .153 0.79
7/2 .450 .728 .124 .)05 0.28 .530 .972 .209 .240 2.91
7/23 .553 2.04 .031 0.40 .631 1.46 .061 0.16
8/6 .708 1.96 .065 .008 0.22 .744 2.00 .075 .244 5.86
8/26 .895 2.96 .242 .023 1.01 3.35 .207 .321
8/27 .860 3.48 .180 .014 0.12 .910 3.39 .160 .206 1.77
RTG II 6/11 .436 .702 .090 .004 0.20 .466 .712 .093 .059 0.51
RTG III 7/30 .696 2.04 .061 0.04 .794 2.25 .053 1.02
8/19 .977 3.63 .098 0.08 1.09 3.87 .076 1.18
9/5 0.02 0.06
S16 8/23 .830 3.60 .115 .007 0.00 1.02 4.60 .150 .141 1.82 a
STS I 6/12 .469 .812 .150 .001 0.36 .457 .666 .133 .163 3.25
7/23 .509 1.31 .032 0.24 .562 1.23 .041 5.92
STS II 9/3 .940 4.04 .140 .013 0.12 .960 4.15 .150 .098 0.56
STS III 9/1 0.07 0.83
MEAN .723 2.14 .118 .016 0.15 .780 2.28 .204 .146 1.60
S .044 .217 .012 .006 0.01 .045 .236 .087 .026 .497
x
-------
70
for reuse in lower lying areas. This sediment yield amounts to
0.019 inch erosion annually, or 52 years to erode 1 inch of soil.
Table 19. Estimated average on farm annual
water balance, Grand Valley
Precipitation
8.3
inches
12 month ET
34.4
Runoff
20.0
Deep percolation
5.1
Delivery seepage
and
spillage
11.2
Total water delivery
71.0
inches
Because the phosphorous complex equilibrates with soil minerals,
phosphorous transport is usually associated with sediment transport.
Mean P concentration of the tailwater runoff increased nine fold
over that of the applied irrigation water. Based on the same run-
off figures previously cited, phosphorous picked up in the tail
water amounts to about 0.9 pounds per acre annually.
In general, sediment concentration in tailwater runoff tends
to decrease with time, during an irrigation as shown in Table 20.
Thus, later increments of runoff contribute less sediment, and
undoubtedly less phosphorous, to the river than does the initial
runoff.
Thus, from chemical analyses, one can conclude that only sedi-
ment load or P concentration are definitely increased by the occur-
rence of tailwater runoff. (Note: Consideration of pesticide con-
centration in the runoff was not included in this investigation).
Even these two parameters are not perfectly reliable indicators of
runoff, as individual measurements occurred in which each was de-
creased as water moved through the field.
Lateral and Canal Seepage Losses
The total groundwater contribution in the Grand Valley is com-
prised of deep percolation beneath irrigated fields, exchange of
water between open drains and the aquifer, and seepage from the
unlined conveyance system. Underf low from the surrounding desert
is a possible source of natural contribution. Several investigators
have evaluated canal and lateral seepage In the valley during the
past two decades or so. Robinson (1955) evaluated seepage from the
central portions of the Grand Valley Canal system. Skogerboe and
Walker (1972) studied seepage from several major canals and laterals
in the eastern part of the valley, and Solomonson and Frazier (1958)
evaluated lateral seepage. With little published information on
canal seepage available for the western portions of the vailey, ARS
-------
71
Table 20. Sediment concentration as a function
of runoff time
Site
Date
Time
Inflow Runoff
g/liter
RTG
III
8/19/75
1130
1135
1158
1300
1305
1400
1500
1505
.04
2.33*
0.93
.03
1.19
0.74
.16
0.72
G22
9/11/75
9/12/75
1500
1930
1400
.12 0.26*
0.08
0.06
G24
9/11/75
9/12/75
1515
1530
1930
1400
.12
1.82*
2.84
2.03
*Indjcates first runoff water.
-------
Table 21. Results of seepage studies on major canals, Grand Valley
Canal
Length of
canal
nn.
Seepage
rate
ft/day
Average
wetted
perimeter
ft
Q
cfa/mi.
Source
of
Data
Government Highilne
(eastern valley)
55
.25
57.0
.87
Skogerboe
& Walker (1972)
Government Highline
(2Ord to Little Salt Wash)
55
.32
47.7
.94
USDAARS,
1974
Government Highline
(Adobe Wash to Little Salt
Wash)
55
.36
47.7
.96
USDAARS,
1974
Price Ditch
12
.13
13.7
.11
Skogerboe,
et
al
(1972)
Stub Ditch
12
.15
11.6
.11
Skogerboe,
et
al
(1972)
Redlands Power
12
.40
14.8
.36
Skogerboe,
et
al
(1972)
Grand Valley System
(Mesa Co. Ditch)
110
.14
11.9
.10
Skogerboe,
et
al
(1972)
(Central reach, GVC)
-1
F..,
.30 1.0
Robinson (1955)
-------
73
conducted ponding tests on the Government Highline Canal following
the 1974 growing season. Table 21 summarIzes the results of var
bus investigations on the major canals. The mean seepage rate,
weighted by canal lengths reported by Skogerboe and Walker (1972)
is 0.6 ft 3 /sec/mile. Using their reported figure of 237 miles of
main canals results In a total seepage estimate of 142.2 cfs.
These canals are operational approximately 200 days annually, re
suiting in an estimated 56,900 acre feet of seepage.
Whether or not seepage from canals contributes to the salt
load in the Colorado River depends on whether and how it moves
toward the River. If, however, all the estimated seepage water
reaches the river at the salinity level of the gravel aquifer at
the Bethel corner well (23 and H Roads), this seepage would contri-
bute 770,000 tons of salt per year to the Colorado River, i.e.,
about the total salt load of the entire valley.
Further seepage occurs in distribution laterals after release
from the main canals. Solomonson and Frazier estimated lateral
seepage losses of .02 cfs per mile. Skogerboe and Walker (1972)
measured seepage losses on nine laterals below the Price, Grand
Valley, and Mesa County canals and found an average seepage loss of
.32 cf s/mile. Near the end of the 1975 irrigation season, three
Elumes were set in lateral 35 for seepage measurements (see Table
22). Results reported show greater seepage than from ponding tests.
However, the flumes used are expected to have a measurement error
in the order of ± .05 cfs at the flow rates encountered. Following
the 1975 irrigation season and again prior to the 1976 season, ARS
evaluated seepage from three laterals below the Government Highline
Canal, with the results shown In Table 22. Weighted mean seepage
from ARS ponding tests following the irrigation season was 0.12
cfs per mile. Combining these data with those of previous invest-
igators results in a mean estimate of 0.25 cfs per mile of lateral.
Assuming that the total length of laterals Is twice the length of
major canals, (total lateral length below GHC in 5.63 mile reach
from Little Salt to Big Salt Wash is 15.42 miles, or 2.75 times
length of main canal) the total annual lateral seepage estimate is
47,600 acre feet per year, almost as much as from the canals them-
selves.
Since previous tests had been conducted in the fall, following
irrigation, for logistical reasons, ABS assumed that the high fall
water tables and possible sealing from sediment may give unrepre
sentatively low seepage rates. During the spring of 1976 ponding
tests were conducted in two of the laterals tested earlier, numbers
30 and 35, as shown In Table 22. Seepage rates measured In these
spring tests were 225X of the rates measured the previous fall.
Undoubtedly, low spring water tables increase the seepage gradient
from many reaches of the main canals as well as laterals, especially
where the water table rises during the season to intersect the
canal. Thus, actual annual canal seepage Is likely to be larger
than estimated.
-------
Table 22. Lateral seepage losses below GHC, 19751976
PONDING TESTS
Lateral
Pond
Test
Pond
Top
Depth
Slope
Wetted
Water
No.
No.
Date
Length
ft
Width
ft
ft
ft/ft
Perimenter
ft
Surface
Drop
ft/da
Seepage
Rates
cf8/rnile
ft
3 2
If t Ida
30 1 10/2931/75 600 5.3 1.5 .0012 6.8 .48 .16 .37
2 600 4.0 1.2 .0030 5.2 .48 .12 .37
3 520 5.1 1.4 .0017 6.5 .46 .14 .36
4 L2. . 0010 7.6 .50 .17 .38
avg 565 5.0 1.5 .0017 6.5 .15 .37
30 1 3/2528/76 100 6.1 1.4 7.7 .90 .34 .72
3 100 5.3 .6 6.2 1.25 .40 1.07
avg 100 5.7 1.0 7.0 .37 .90
-1
33 1 10/2831/75 720 4.3 1.2 .0015 5.5 .46 .12 .36
(main) 2 137 4.4 1.4 .0020 5.8 .74 .20 .56
3 350 4.8 1.6 .0010 - 6.4 .68 .20 .51
4 300 3.0 0.8 . 0015 3.8 .82 .15 .65
avg 377 4.1 1.2 .0015 5.4 .17 .52
35 1 10/3031/75 268 5.0 1.4 .0040 6.4 .43 .13 .34
2 1100 5.2 0.8 .0006 6.0 .17 .05 .15
3 1000 5.1 0.9 . 0005 6.0 .21 .07 .18
avg 789 5.1 1.0 .0017 6.1 .08 .22
35 2 3/2426/76 100 4.9 1.4 6.3 .46 .14 .36
3 2.2. Li .35 J i
avg 100 5.0 1.3 6.4 .12 .32
-------
Table 22. Lateral seepage losses below GHC, 19751976
Page 2
Date
Time
Flume
Depth
ft
No. 1
Flume
Depth
ft
No. 2
Flume
Depth
ft
No. 3
Seepage
Rate*
Section
(1.0 ml)
afs/mi
1
Section
(0.9 ml)
0f8/mi
2
Flow Rate
cfs
Flow Rate
cfs
Flow Rate
cfs
10/24
1530
.72
2.20
.69
2.05
.15
10/26
1530
.59
1.59
.55
1.41
.18
10/27
1630
.54
1.37
.50
1.20
.17
10/28
0900
.99
3.73
.93
3.37
.92
3.31
.36
.07
-------
76
Ground Water and Return Flow
From previous discussions, it is apparent that canal and lat-
eral seepage, deep percolation, precipitation, and tailwater run-
off do not contribute directly a large part of the pollutant (salt)
loading of the Colorado River in the Grand Valley. Investigation
of water levels in open pits adjacent to the river at several lo-
cations suggests that groundwater gradients are always toward the
river. Thus direct recharge from the river is not expected to be
significant. Of major importance, however, is the route and mode
of water movement after its loss from the irrigation system and
before It enters the river.
To give further insight into groundwater movement toward the
river, in 1974, Edmund Schneider, a graduate student In the Depart-
ment of Earth Resources, Colorado State University, commenced a
study of surf icial geology in the Grand JunctionFruita area as
part of the current ARS studies. His objectives were 1) to delin-
eate exposures of Mancos Shale and local stream and Colorado River
alluvium; 2) to define the subsurface topography of the Mancos
Shale erosion surface where it underlies alluvium; 3) to determine
the degree of weathering, general permeability, and the extent and
nature of surface and subsurface water seepage In the weathered
zone of the Mancos Shale; and 4) to determine the areal extent and
thickness of the Colorado Riverdeposited cobble aquifer which
underlies the southern portion of the study area. The geologic
complexity of the area is perhaps best described In Schneiders
words:
The area of investigation encompasses 150
square miles of the Grand Junction Fruita area
of the Grand Valley of the Colorado River in west
central Colorado. Bedrock consists entirely of
marine Upper Cretaceous Mancos Shale which is
locally covered by Quaternary alluvium. The
saline Mancos Shale and alluvium have a profound
influence on groundwater salinity and drainage
problems in the Grand Valley.
The relatively broad form of the Grand Valley
developed during several cycles of erosion asso-
ciated with Late Pliocene or Early Pleistocene
uplifting of the Uncompahgre Plateau.
A portion of the study area which extends
three miles north and parallel to the Colorado
River Includes up to 70 feet of tributary allu-
vium overlying 15 to 20 feet of Colorado River
bedload materials (local cobble aquifer) deposited
on eroded Mancos Shale. The northern edge of the
burled Colorado River deposits Is bounded by a
dissected Mancos Shale terrace. The terrace
was dissected by tributary streams originating
-------
77
in the Book Cliffs to the north which downcut
to the level of the Colorado River channel at
its northernmost position. The bedload materials
were deposited as the Colorado River migrated
laterally southward prior to the establishment
of its modern position.
In response to the lateral shift of the Colorado
River, the southward flowing tributaries became
aggraded upstream to reestablish equilibrium
grade. As a result, the south side of the valley
was ultimately filled with tributary alluvium.
Construction of a bedrock contour map revealed
that a major buried tributary valley is present
in the Little Salt WashAdobe Wash area near Fruita.
The presence of this valley provides a basis for the
development of a model for the subsurface config-
uration of the Grand Valley. In addition, it
provides a means of explaining how the cobble
aquifer system is hydrologically and stratigraph
ica] .ly connected with the tributary alluvium north
of the cobble aquifer.
Drill holes constructed in the study area
revealed that Colorado River alluvium could be
distinguished from tributary alluvium on the
basis of gravel composition. River gravels
are derived from Precambrian granitic, gneisslc,
and Tertiary basaltic rocks whereas tributary
gravels are entirely derived from sandstone
and silts tone members of the Upper Cretaceous
Mesaverde Group and Tertiary Wasatch and Green
River Formations.
Drill holes augered into the Nancos Shale
revealed that there is an artesian waterbearing
zone on the weatheredshale and freshshale inter-
face from 5 to 15 feet below the weatheredshale
surface. Recharge is by seepage along exposed
shale reaches of unlined canals. Even though the
shale is vertically impermeable, recharge occurs
along laterally interconnected bedding planes and
joints. The shale water system is too meager to
be considered a significant aquifer, but salts
leached from the Mancos contribute to groundwater
salinity. Analysis of shale water revealed that
it was saturated with respect to calcite and
gypsum.
Monitoring of water levels in drill holes
showed that the artesian shale water dried up
after the canals were turned out in October. In
comparison, the water table in the alluvium dropped
-------
78
only slightly during the winter months. Recharge
to the unconfined water system is primarily from
irrigation waters as recharge from local intermittent
washes is negligible. Therefore, the lack of a sig-
nificant drop in the water table was attributed to
poor drainage controlled by the predominance of
thick sequences of clay and silt deposits inter
bedded with thin, discontinuous, and poorly sorted
sand and gravel lenses. This apparent poor drainage
significantly reduces the effectiveness of groundwater
flow as a means of flushing out dissolved solids, and
is the cause of local high water table conditions.
Schneider drilled 23 observation wells throughout the area
between Adobe Creek and Little Salt Wash (see Figure 12). Water
levels in these wells are being measured regularly, and samples
being taken for chemical analyses. Table A2 in the Appendix shows
the water level fluctuations measured from sununer 1974 through
spring 1976. Figure 13 illustrates that water table response, even
at some distance from the canal, is quite rapid once the canal is
filled (April 14). Considering Schneiders analysis of the upper
Mancos shale, this rapid response is apparently due in part to
seepage through the bedding planes and joints within the shale.
Chemical analyses of samples collected from these wells are
given in Table A3 of the Appendix. Changes in electrical conduct-
ivity (EC) with time in some wells (1, l9H, 21, 22H) indicates a
seasonal dilution by less saline water, particularly during summer
and fall as seepage water migrates through the aquifer. Other wells
(llA, llB, 12, 13, 15) show little change in EC with time. The
fact that those wells showing fluctuating EC are not located in
any particular portion of the study area illustrates the complexity
of the primary transport paths for return flow.
Wells 20 and 21 lie clearly in the area of the cobble aquifer,
but water from these wells was unsaturated with CaSO 4 (gypsum) at
all six sampling dates. Previously, water from all wells in the
cobble aquifer was saturated with CaSOk in areas east of the loca-
tions of wells 20 and 21.
Three other wells (1, 3, and 16) above the cobble aquifer
always showed water samples unsaturated with CaSOi. Some other
wells (hA, 17, 18, 19, and 22) had water saturated with CaSO 14 for
part of the sampling dates. For example, well 22H was unsaturated
with CaSO on 10/12/75 and 11/18/75 but the water was saturated or
near saturation with CaS0z at other sampling dates. This well is
located near the Grand Valley Canal, but above it.
Although individual wells showed rather large changes in EC
with time, the mean EC at the various sampling dates were not
significantly different from the overall mean of 5.72 imnhos/cm.
This might suggest that, although the path of water movement has
considerable influence on water quality in the groundwater, the
-------
79
D I I -
Drill Hole Location
Figure 12. Drill hole locations. Little Salt WashAdobe
Wash areas.
M Road
L Rood
J Road
N
-------
80
Dote
JASON D
1976
J F MA
I I I I U I U I I I I I I I I I
I. I
Well: DHI
Location 20.5 & M.75
2 . . mile South of GHC
3.
4.
5.
6
7.
8
9.
I0
Figure 13.
Response of water level in observation well
to seepage
1975
J F M A M I
5/20
4-
I .-
I. .
SI
4-
a
0
4-
SI
6/3
5/I
10/9
4/19
2/14
Il/I a
4/14
12/16
Dry
-------
81
amount of movement (as interpreted from date of sampling) does not.
One could carry such an inference further to say that, since the
quality of return flow doesnt change in inverse proportion to the
rate of return flow, i.e., seepage and deep percolation, then the
salt load to the river is proportional to volume of deep percolation
and seepage rather than their quality as they leave the root zone
or canal, respectively. Thus, management of pollutants in return
flow depends primarily on control of water rather than chemical
modification.
The natural washes in the valley run generally perpendicular
to the canal system and the river and frequently cut both the gravel
aquifer in the lower reaches and the fractured shale in the upper
reaches. As a result, most washes flow year around and provide an
important route of transport of salt to the river. Flumes installed
in nine washes were used to measure base flows into the washes dur
trig the winter months. Periodic samples were collected at each
station for chemical analyses. Discharge measurements and calcul-
ated salt loads at four sampling periods for each measuring station
are shown in Table 23 (complete chemical analyses are given in
Table A4 of the Appendix). In each case, the flow increases at
successive downstream positions, indicating that base flow (soil
and aquifer drainage) occurs throughout the irrigated area. During
this winter period, no significant trend in flow rates could be
detected. Because of the rapid response of groundwater levels to
canal diversion, the subsurface drainage removed by these washes
is undoubtedly larger during the irrigation season than indicated
by these measurements.
No significant trend was observed in EC of the drainage water
during this period. This is further indication that whatever water
percolates to the groundwater reaches an approximate equilibrium
concentration, regardless of the rate of water movement (i.e. the
exposure time). However, Little Salt, Persigo and Indian washes
showed statistically significant trends of increased concentration
from the Government Highline Canal toward the river. This indicates
pickup of more saline water (i.e. water from the cobble aquifer)
in the lower reaches of these washes. These results correspond to
results of seepage meter tests conducted in selected reaches of
these three washes. During December 1973, a thermal infrared scan-
ner was used to detect warm spots in the cold surface waters of all
the Grand Valley washes, which were indicative of concentrated in-
flows of warmer groundwater. Subsequently, meters capable of meas-
uring either positive or negative seepage rates and of collecting
a sample of influent water were installed at the concentrated
inflow locations indicated by thermal IR imagery. Typical chemical
analyses of water collected are shown in Table 24. Each of these
three washes had locations of concentrated inflow of water hav Lng
considerably higher salinity than the adjacent surface flows.
An attempt was made to extrapolate the drain flow and salt
loading measurements to an annual salt loading contribution by the
-------
Table 23. Drain flow and salt measuranenta, winter 19751976
12/17/75
1/7/76
1/22/76
2/5/76
Q, efe EC, iisthoa
S.L.
tuna/hay EC
S.L.
tons/day Q c ia EC. mmhoa
5.1.
tons/day cia EC iiimhos
S.L.
55/daY
Little Salt Wash
1 0.34 3.17 2.70 0.25 3.47 2.17 0.22 3.04 1.67 0.21 3.00 1.58
2 0.96 3.93 9.44 0.66 4.16 6.87 0.62 3.87 6.00 0.47 3.66 4.30
3 2.03 4.08 20.72 1.42 3.44 12.22 1.21 4.36 13.20 1.40 4.06 14.22
4 4.95 4.65 57.58 3.50 4.80 42.03 3.80 4.53 43.06 4.00 4.36 43.63
Adobe Wash
1 0.20 4.58 2.29 0.17 4.79 2.04 0.12 4.73 1.42 0.13 4.58 1.49
2 1.53 4.37 16.73 0.95 4.60 10.93 1.00 4.34 10.86 0.84 4.27 8.97
3 2.80 4.65 32.57 2.28 4.87 27.78 2.28 4.46 25.44 2.32 4.58 26.58
Hunter Wash
1 0.25 4.70 2.94 0.07 5.12 0.90 0.07 4.81 0.84 0.01 3.27 0.08
2 2.55 4.63 - 29.54 1.90 4.79 22.77 1.85 4.78 22.12 1.80 4.56 20.53
3 4.72 4.10 5.03 51.59 3.75 4.85 45.50 3.90 4.71 45.95
Peraigo Wash
1 0.47 4.45 5.23 0.35 4.46 3.90 0.36 4.36 3.93 0.35 4.23 3.70
2 3.15 4.80 37.82 2.80 4.99 34.95 2.70 5.00 33.77 2.80 4.66 32.64
3 7.60 5.37 102.10 4.12 5.51 56.79 3.93 5.42 53.29 4.11 5.36 55.11
Leach Creek 2.52 4.55 28.68 2.22 4.56 25.32 2.01 4.32 21.72 1.81 4.30 19.47
T,w14 a i Wash
1 0.23 4.79 2.76 0.14 4.64 1.63 0.11 4.99 1.37 0.11 4.37 1.20
3 1.79 6.09 27.27 1.61 5.88 23.68 (1.60) 5.92 (23.70) 1.74 5.73 24.94
Lewis Wash 0.25 4.58 2.86 0.23 4.48 2.58 0.19 4.43 2.11 0.18 4.35 1.96
g Salt Wash
West
1 0.55 3.50 4.82 0.45 3.69 4.15 0.53 3.43 4.55 0.65 3.77 6.13
2 3.90 3.94 38.44 2.40 4.02 24.14 2.18 3.84 20.94 2.35 3.56 20.93
Big Salt Wash
East
1 0.40 3.70 3.70 0.30 4.77 3.58 0.31 4.46 3.46 0.25 4.37 2.73
2 2.50 3.74 23.39 1.63 3.93 16.22 2.60 4.02 26.15 1.45 3.89 14.11
-------
Table 24. Water composition from adjacent sites in Persigo, Little Salt, and Indian Wash drains,
Grand Junction, 1975
Drain
and
Location
Site
EC
mmhos/cm
me/i
pH
pCaSOt
FCC 2 , matm.
Ca
Ng
Na
Cl
SO
NO 3
HCO 3
Persigo5
stream
meter
1.73
3.50
8.38
15.57
4.77
15.71
5.65
15.65
3.22
4.08
11.60
38.32
.21
.26
3.60
4.44
8.02
782
5.35
4.85
1.56
2.64
Persigo7
stream
meter
1.72
1.93
8.08
9.58
4.77
5.43
5.65
6.30
3.10
3.40
14.42
14.62
.17
.14
3.50
4.04
7.61
7.21
5.29
5.24
3.91
11.08
Little Salt7
stream
meter
1.10
1.26
4.09
5.24
2.14
2.55
4.13
4.56
3.44
2.88
7.06
7.56
.13
.14
3.20
3.40
7.89
7.41
5.73
5.63
2.02
6.36
Little Salt8
stream
meter
1.03
1.50
3.94
6.99
1.89
3.29
4.13
5.00
2.80
3.02
6.05
8.07
.11
.13
3.20
4.00
7.54
7.31
5.83
5.44
4.58
9.14
C. V. Canal
Indian Wash
Indian Wash
Indian W.
G. V. Canal
spring
0.37
1.83
2.50
1.84
9.67
13.13
1.63
6.52
8.16
.98
4.78
9.13
.61
2.26
2.98
1.26
14.87
22.81
.11
.22
.27
2.10
3.36
4.00
7.83
7.82
7.55
6.60
5.22
5.01
1.75
2.27
4.76
-------
84
washes. The average total daily winter salt load of the nine washes
reported in Table 23 (assuming an EC of 1 nunho/cm equals total dis-
solved solids of 928 ppm) is 285.9 tons per day. Assuming that
this rate and concentration of base flow is continuous throughout
the year, the total salt load removed through these washes is
104,000 tons per year. There are at least 18 major natural washes
in the Grand Valley, plus numerous open artifical drains. There-
fore one might assume that the total winter base flow rate is about
twice that measured in this study. If groundwater flow during the
irrigation season (because of higher groundwater levels) is sub-
stantially greater than during the winter months, these drains may
be the mode of tranport for practically all of the calculated salt
load contributed by the Grand Valley. More complete studies of
total drain discharge are currently being conducted by the U. S.
Bureau of Reclamation and U. S. Geological Survey.
It was originally intended to attempt to employ various types
of tracers to determine specific flow paths of the various components
of the groundwater. However, after evaluation of the geologic study,
observation well data, results of canal seepage tests, and the
drain investigation, the project leaders concluded that the expense
of adequate test equipment and boring would be prohibitive, the
results would be very site specific, and the probability of conclu
sive results at any selected site was small. Therefore, tracer
studies were not given further consideration.
-------
SECTION VIII
APPLICABILITY OF METHODS TO SINILAR AREAS
One of the overall objectives of this study was for the research-
ers involved to make a subjective appraisal of the techniques em-
ployed in this study and evaluate their applicability to similar
evaluations in other areas. Many aspects of the study utilized
proven methods such as neutron attenuation instruments for soil
moisture measurements, ponding tests for determining canal and
lateral seepage rates, and standardized laboratory methods for
chemical analyses. Orifices, critical depth flumes and commercial
propellor meters were used for measurement of surface components
of the water balance. Perhaps a word of caution is in order regard-
ing use of flumes for estimating deep percolation losses. Unless
calibrated in place, one can expect an average accuracy of about
± 5% from critical depth flumes. Where large amounts of runoff
occur, and ET estimates are subject to errors on the order of
± 10%, the gross measurement error, which Is normally lumped into
the deep percolation term, can be quite large relative to the actual
deep percolation. As an example, if 63 inches irrigation water is
applied, one third is tailvater runoff, and ET is estimated at 32
inches, measurement errors expected may result in estimated deep
percolation loss ranging from 2.5 to 17.4 inches, or a calculated
leaching fraction ranging from 0.07 to .38. Of course, the prob-
ability of all errors being in the direction to produce these ex-
treme estimates is small, but the example illustrates that calcula-
tions by this technique are not exact.
The hydraulic lysimeters used in this study are of a type
previously described by Hanks and Shawcroft (1965) with an improved
readout system to allow maintaining the readout underground for
better control of temperature influences. These lysimeters have
a realistic resolution of at least 0.2 mm (.008 inches) of ET.
Although resolution is not as good as the best electronic weighing
systems, these lysimeters are quite economical, costing 10% or
less the price for an electronic device, and requiring no electrical
power for operation. The lysimeters used in this study were fab-
ricated of exterior grade plywood with an asphaltic sealant applied.
This appears to be satisfactory for about two seasons use, although
marine grade plywood is recommended to reduce warping. Lysimeters
anticipated to be used for longer periods should be fabricated of
impervious materials, such as steel, or If properly braced, fiber-
glass.
The vacuum extractors serve two purposes, i.e. to measure the
amount of percolating water and to provide a sample for chemical
analysis. With proper pretreatment of the ceramic tubes (Duke
and Haise, 1973), it is felt that the chemical aspects of extractor
samples are representative of the mobile soil water. One must be
aware, however, of the possible chemical changes that occur after
85
-------
86
sample collection, particularly carbonate reactions effected by
reduced pressures in the collection system.
Accuracy of the extractors with respect to rate of percolation
is much less clearcut. Interception accuracy depends on the main-
tenance of a zero horizontal gradient at the top of the metal
trough. Because of indeterminable head loss in the vicinity of the
candles (which is also a function of the rate of percolation),
applied vacuum must be greater than the ambient soil auction. By
the nature of the soil physics and physical properties pertinent,
coarse textured soils are many times more tolerant of errors in
applied vacuum than are fine textured soils. The present research-
ers have had quite consistent results from these devices when in-
stalled in the clean, uniform Valentine sand, but their application
in the clays and clay barns of the Grand Valley requires very care-
ful measurement of soil water suction both inside and outside the
metal trough. Obviously, the extractors are limited to operation
within the range of soil water suction between saturation and the
vapor pressure of a free water surface (about 0.8 atmosphere).
Thus, the device cannot be expected to operate satisfactorily under
nonirrigated lands in arid or semiarid regions, nor when located
very near to a water table or under conditions of very high percol-
ation as might be encountered beneath a canal or groundwater recharge
structure. It is particularly important that the device be installed
by the undisturbed technique, described in Section V, in fine
textured soils, soils with significant structural elements, for
studies where chemical aspects are important, or where gravity irri-
gation techniques are used. Open trench installation will invariably
disturb both the chemical and physical properties to the point that
results may not be representative for many years, if ever. Because
of the time and expense of installation and the constant attention
required, the vacuum extractors are not suitable as a survey tool,
but under the conditions described may prove useful in research
situations.
The technique of using chloride concentration as a means of
measuring water use by plants is a technique of long standing. It
is frequently applied to pot and lysimeter studies where total
effluent can be collected, usually with a water table or other
constant water content at the bottom of the soil container. The
application of this technique to field soils has been apparently
successful in some areas, notably the desert southwest. In these
areas, precipitation is quite insignificant compared with the high
annual ET, irrigation (and presumably percolation) proceeds year
around, although less frequently during the winter, infiltration is
not influenced by winter freezethaw cycles, and we suspect that
chloride concentration in the irrigation water changes rather grad-
ually with time due to the mixing in the many reservoirs providing
the typical water supply for these regions.
In the Grand Valley, however, precipitation, though low,
approaches 25% of the annual ET, providing considerable dilution
-------
87
and flushing of accumulated soil salts. High initial infiltration
rate, deep plowing and cracking of these expansive soils promotes
deep percolation early in the growing season. Because the irriga-
tion supply of the Grand Valley is from direct runoff, with no in-
line storage, this early streamfiow is primarily from snowmelt and
is of very high quality. As snowmelt recedes and groundwater flow
becomes the primary water source for the river, chloride concentra-
tion in the late summer will typically increase ten fold. These
factors complicate leaching fraction calculations by the chloride
technique considerably. Not only must many samples be analyzed
to take into account the soil variability encountered, but one must
also develop a history of precipitation, irrigation water quality,
and even deep percolation to adequately apply the chloride profile
technique for leaching fraction calculations. Such calculations are
further complicated by high water tables, posing the probability
of net upward flow of groundwater, and by extreme soil stratifica-
tion, which may result in substantial lateral movement of soil water.
Thus, we have concluded that the chloride profile technique,
though it may provide a relative measure of leaching and may be more
accurate than conventional water balance techniques, is not direct
ly applicable for leaching fraction calculation in the Grand Valley.
One aspect of the results, however, must not be deeniphasized. Each
of the factors complicating the procedure tends to result in an
overestimate of the leaching fraction. Thus, even if a shallow
water table is present, the technique, with adequate numbers of
samples, should give an upper limit to the expected leaching frac-
tion.
The computer scheduling technique, and methods of calculating
ET necessary for its application, has been used for more than a
decade, but is still viewed with skepticism by some. Although
average ET rates for a given crop at a particular time of year may
be perfectly adequate scheduling information for the desert south-
west where precipitation is negligible and climate varies little
from year to year, most of the irrigated acreage in the western
U. S. has sufficient precipitation and climatic variability that
constant estimates of ET are not adequate for irrigation scheduling.
The ARS Scheduling Program has proven quite successful in widely
separated areas, and has been adopted, either directly or in modi-
fied form, by the Bureau of Reclamation and by numerous commercial
farm consultants. Without a doubt, ET estimates by this procedure
are much more accurate than the water measurement devices provided
on the majority of western surface delivery sytems.
Although not treated in detail in the studies reported here,
several tracer techniques are worthy of mention at this point.
During early phases of the USBR study, we employed an airborne
thermal infrared scanner to detect small differences in surface
temperature of the flow in natural drains to pinpoint areas of con-
centrated groundwater inflow into the drains. This equipment is
capable of detecting temperature differences on the order of 0.1°C
-------
88
and resulted in quite clear delineation of areas where warm ground-
water enters the washes. The technique is widely used to detect
seepage from impoundments and mixing of tributary flows in rivers.
Further tracer techniques originally envisioned for this study
included introduction of tagged ions, uncommonly encountered halo-
gens, fluorescent dyes and neutron activation analyses to detect
the presence of artificially introduced nonradioactive ions. These
techniques were discounted, not because of lack of confidence in
the tracer technique, but because the complex geological character
is tics would give very site specific results, with little chance of
extrapolation to the valley as a whole. The one tracer discovered
tha; seemed ηo have promise was the ratio of naturally occurring
Ca and Mg ions in the water. Early analyses showed quite con-
sistent Ca/Mg ratios of the order of 0.5 for water directly associated
with river flow and about 2.0 in water known to have passed through
soil materials. It was felt that this ratio, even though the concen-
trations varied widely, might readily identify whether a given
sample of water had passed through the groundwater system or was
strictly associated with surface flows. As studies were expanded
to cover other areas 2 of the valley, however, numerous inconsistencies
between Ca+ 2 and Mg+ ratios developed. Although these inconsis-
tencies may well have resulted from local geologic conditions, the
concept of Ca/Mg ratio as a tracer was eventually dropped.
-------
SECTION IX
REFERENCES
1. Duke, H. R. and H. R. liaise. 1973. Vacuum extractors to assess
deep percolation losses and chemical constituents of soil water.
SSSA Proc. 37(6) 963964, NovDec.
2. Hanks, R. J. and R. W. Shawcroft. 1965. An economical lysimeter
for evaporation studies. Agron. J. 57:634636.
3. Jensen, N. E. 1969. Scheduling irrigations using computers.
J. Soil and Water Conserv. 24(8):193195.
4. Kincaid, Dennis C. and Dale F. Heermann. 1974. Scheduling
irrigations using a programmable calculator. Agricultural
Research Service, USDA, ARSNC12.
5. Knobel, E. W., R. K. Dansdill, and N. L. Richardson. 1955.
Soil survey of the Grand Junction area, Colorado. USDA Soil
Conservation Service, Series 1940, No. 19.
6. Kruse, E. C. 1974. Alleviation of salt load in irrigation
water return flow of the upper Colorado river basin. USDAARS
FY 1974 Annual Report to Bureau of Reclamation, U. S. Department
of Interior.
1. Kruse, E. C. 1975. Alleviation of salt load in irrigation
water return flow of the upper Colorado river basin. USDAARS
FY 1975 Annual Report to Bureau of Reclamation, U. S. Department
of Interior.
B. Kruse, E. C. 1976. Alleviation of salt load in irrigation
water return flow of the upper Colorado river basin. USDAARS
FY 1976 Annual Report to Bureau of Reclamation, U. S. Department
of Interior.
9. Miller, Dalton C. 1916. The seepage and alkali problem in the
Grand Valley, Colorado. USDA Office of Public Roads and Rural
Engineerings.
LO. Robinson, A. R. 1955. ARS-USDA Annual report on drainage and
water conveyance. Fort Collins, Colorado (unpublished).
lL Schneider, Edmund J. 1975. Surflcial geology of the Grand
JunctionFruita area, Mesa County, Colorado. Department of
Earth Resources, Colorado State University, Fort Collins,
Colorado.
89
-------
90
12. Skogerboe, G. V. and W. R. Walker. 1972. Evaluation of canal
lining for salinity control in Grand Valley. Office of Research
and Monitoring, U. S. Environmental Protection Agency, EPAR2
72047.
13. Skogerboe, C. V., V. R. Walker, R. S. Bennett, J. E. Ayars
and 3. H. Taylor. 1974. Evaluation of drainage for salinity
control in Grand Valley. Office of Research and Development,
U. S. Environmental Protection Agency, EPA660/274084.
-------
SECTION X
APPENDIX
91
-------
TABLE Al
WATER ANALYSES, NONWEIGHING LYSINETERS, S16, 1975
Each date represents mean values of 1 to 5
All chemical analyses reported in Table Al
California.
sampling dates.
were conducted at
EC
Plot Date mmhos/cm
me/i EC me/i
Cl SO NO 3 Plot Date imnhos/cm Cl S0 1 NO 3
Si
6/19
7/7
7/23
7/18
9/2
9/9
9/23
10/30
11/18
3.32
3.48
3.18
3.01
2.79
2.80
2.62
2.60
2.83
15.38
14.60
11.20
8.71
6.94
6.50
5.49
6.89
8.38
11.44
8.09
9.00
10.37
8.05
9.09
10.02
11.14
10.17
4.31
4.11
2.55
2.96
4.35
5.33
2.95
2.63
2.42
S4
6/19
7/7
7/23
8/18
9/2
9/23
10/30
11/18
3.31
3.67
2.99
2.51
2.64
2.73
2.65
2.67
15.40
16.00
12.00
12.75
11.65
12.00
11.70
11.25
10.70
9.38
9.59
10.80
8.60
10.10
10.20
9.75
4.09
3.58
1.76
1.40
2.12
.471
.611
.740
S2
6/19
7/7
7/23
8/18
9/2
9/9
9/23
10/30
11/18
3.78
4.04
3.97
3.94
3.93
3.80
3.66
3.46
3.53
16.00
16.02
15.57
15.72
15.13
13.90
13.15
12.30
11.84
22.70
23.47
18.37
21.36
20.10
18.40
18.50
18.22
18.12
.513
.439
.476
.312
.553
.525
.366
.385
.590
S5
6/19
7/7
7/23
8/18
9/2
9/9
9/23
10/30
11/18
3.32
3.62
3.13
2.82
2.82
2.70
3.67
2.87
2.96
15.50
16.05
11.07
10.50
10.45
10.30
10.00
9.22
10.11
10.00
14.00
11.34
12.35
10.22
14.00
21.60
12.87
14.28
3.66
4.20
1.52
.419
.530
.650
1.78
1.13
.613
S3
6/19
7/7
7/23
8/18
9/2
10/30
11/18
6.08
6.26
3.94
5.16
3.25
4.89
3.28
26.40
25.18
14.37
21.30
9.91
19.30
12.00
43.80
39.40
17.13
32.40
10.80
32.00
14.60
3.02
2.66
2.12
2.15
2.52
1.12
.91
S6
6/19
7/23
8/25
8/27
9/2
9/9
9/23
10/30
3.50
3.52
3.37
5.18
5.14
4.89
4.58
3.81
15.20
11.60
11.80
12.70
11.90
10.80
9.89
9.48
10.70
9.29
12.80
32.10
35.20
34.54
36.30
29.70
2.84
2.37
5.85
5.35
8.11
6.41
4.50
3.71
0
the U. S. Salinity Laboratory, Riverside,
-------
WATER ANALYSES FROM VACUUM EXTRACTORS, 1975
7/25
8/13
8/18
8/26
8/28
9/3
9 / 12
9 / 17
9 / 24
H 2 0 ieached,cm
7/17
7/23
7/25
8/13
8/18
8/26
9/3
9/12
9 / 16
9/24
10 / 2
H 2 0 leached,cm
3.38
3.15
1.47
1.27
1.26
1.22
1.45
1.46
1.42
9.3
2.25 2.21
1.91
2.12 1.87
1.92
1.87
1.76
1.53
1.96 1.61
1.62
1.60
1.65 1.65
3.5 14.2
10 0
9.42
3.82
2.82 3.48
3.20
2.47 3.20
2.85 2.56
2.54
3.23
0.5
1.32
1.31
1.42
1.21
.99
1.45
1.54
1.59
1.45
13.9
12.4
5.57
5.26
4.09
3.50
3.84
6.13
1.33
1.29
1.07
.92
1.06
1.97
2.82
2.88
1.92
10.9
8.32
5.54
3.80
5.68
3.03
8.4].
6.82
6.82
7.87 7.62
4.89
8.86 7.29
7.06
6.56
3.41
2.73
9.09 7.73
6.82
6.88
6.25 4.55
7.71
4.63
.564
.577
.580
7.39 .220
9.66 .545
.270
.325
5.44
4.04
.832
.350
.140
.198
.384
.338
400
.457
2.72
.536
.130
.260 .070
.182
.126
200
.100
.. a. fl
O (j )
.164
.109
.315
.140
.107
.166
north end of field
M = middle
S = south
(top)
M S
Site Date EC, mmhos/cm
N N S
N M S
N M S
NO 3 , me/i
Cl, me/i
SOj ,, me/i
CSUB
LDS
3.79
3.33
1.82
1.72
1.20
1.26
1.38
2.04
7.3
8.84
8.26
8.36
10.1
13.0
10.1
6.71
7.39
4.13
9.09
6.82
11.3
5.02
2.11
2.89
7.68
6.44
5.48
5.40
5.26
4.22
6.42
5.48
3.02
3.01
2.39
2.20
2.70
2.53
2.14
2.31
1.42
.236
.271
2.83
3.02
4.25
6.05
3.66
2.85
3.14
6.82
6.82
7.2
-------
WATER ANALYSES PROM VACUUM EXTRACTORS, 1975
7/8
7/17
7/28
7/30
8/18
9/12
9/16
9/25
10/2
H 2 0 ieached,cm
4.30
4.16
4.20
8.94
6 86
5.12
5.76
5.32
51.1 16.7 3.58
36.3 17.6 2.04
2.09
4.91 1.58
5.34 1.09
1.14
6.68 1.29
.520
.237
.149
.354
= north end of field
N = middle
S south
(top)
M S
Site Date EC, mmhos/cm
N M S
N M S
N N S
Ci, me/i
50 kg me/i
NO 3 , me/i
LS
EB
9.85 3.15 11.4
9.42 3.21 11.9
10,3
82.7 10.1 21.4
81.2 11.1 20.2
29.2
9.48 3.04
10.73 3.19
3.22
3.18
3.15
3.29
2.25 6.84
3.90
3.52
3.05
3.13
3.40
8.90
3.28
3.41
3.67
3.52
3.50
3.65
44.0 15.6
47.4 14.1
18.0
19.8
21.8
22.6
79.1
82.1
9.79
11.9
13.2
13.2
14.2
13.1
3.84
4.05
4.16
4.24
4.30
4.19
5/7
5/20
5 / 30
6/5
6/12
6/16
7/3
7/8
7/18
9/17
9/24
1120 leached,cm
9.82
9.12
7.56
5.88
6.48
6.96
86.5
74.7
71.8
71 0
70.5
69.5
39.4
39.1
17.2
25 2
23.8
21.6
24.3
27.2
29.5
30.9
33.0
30.1
29 5
28.4
7.69
8.60
ii 5
8.53
8,24
8.18
9.40
8.61
8.50
8.72
8.45
8.16
6.95
7.06
5.01
5.6
852
820
.226
116
.267
888
1.03
.911
.774
1.13
833
3.29
3.26 3.38
3.12 2.77
2.96
6.2 4.8
27.8
28.4
27,4
27.4
31.6
28.1
4.55
5.64 4.04
7.74 4.16
5.27
71.1
71.6
65.8
56 0
69.4
66.9
58.3
57.8
42.1
3.56
4.09
4,26
3.48
3.99
3.84
28.5
19.8 30.6
23.2 21.9
23.9
1.73
1.07
1.67
1.61
2.12
2.30
.960
.710
.924
.940
2.31 .840
.336 1.10
1.16
-------
WATER ANALYSES, VACUUM EXTRACTORS. G-24 (middle) 2
Date Volume EC Ca Mg
Na
K
E
HCO 3
Cl
S0 1
NO 3
E
SAR
Ca/Mg
Cl Ratio
61774
100
4.48
19.7
11.2
17.4
.2
48.6
7.8
23.8
12.3
3.8 -
47.8
4.4
1.8
.10
61974
248
5.06
28.0
13.3
17.8
.7
59.8
11.5
19.1
18.4
9.6
58.6
3.9
2.1
.12
70374
2098
5.20
28.0
12.3
17.6
.1
58.0
11.6
19.9
15.5
9.3
56.3
3.9
2.3
.12
100374
45
2.21
11.0
4.2
8.9
.1
24.2
9.0
7.1
6.8
1.4
24.3
3.2
2.6
.33
101774
225
4.98
28.2
11.7
18.5
.8
59.1
13.5
18.8
18.3
9.0
59.6
4.1
2.4
.12
60275
250
3.13
15.6
7.6
13.5
.4
37.2
13.0
7.4
11.2
5.7
37.3
3.9
2.0
61675
414
2.95
13.9
7.6
12.4
.4
34.2
15.2
4.7
7.9
6.6
34.4
3.8
1.8
61975
353
2.95
14.4
7.7
11.4
.3
33.9
14.5
5.2
8.3
6.1
34.0
3.4
1.9
62675
78
2.88
15.6
8.1
11.9
.4
36.0
16.0
5.2
8.3
5.2
34.7
3.4
1.9
71075
2585
2.76
14.1
6.7
10.7
.4
31.8
16.1
4.4
6.7
4.7
31.9
3.3
2.1
72375
2765
2.59
13.8
9.1
10.2
.3
33.5
17.3
3.7
7.6
4.0
32.7
3.0
1.5
80575
3170
2.47
13.3
8.3
9.2
.3
31.1
18.5
3.3
6.6
2.6
31.1
2.8
1.6
0
81175
107 2.55 14.4 8.7 10.1 .4 33.6 20.2 3.6 7.1 2.7 33.6 3.0 1.6
-------
WATER ANALYSES, VACUUM EXTRACTORS, G24 (S) 3
Date Volume EC Ca
K
SOk NO 3 Z SAR Ca/Mg C l Ratio
Mg
Na
E+
U 3
Cl
61774
98
1.28
6.5
3.9
3.8
.4
14.5
8.7
2.6
3.6
.2
14.6
1.7
1.7
61974
222
1.43
6.9
4.1
4.4
.02
15.5
8.4
3.4
3.1
.6
15.6
1.9
1.7
62774
483
1.35
6.1
4.0
4.7
.1
14.9
8.5
2.9
3.4
.3
15.2
2.1
1.5
70374
435
1.42
6.6
4.7
3.7
.03
15.1
8.9
2.9
3.2
.1
15.1
1.5
1.4
71074
205
1.66
9.2
5.6
4.3
.1
19.1
10.8
3.6
4.4
.3
19.2
1.6
1.6
71774
1530
1.75
8.9
5.6
4.5
.04
19.0
11.2
3.9
4.2
.5
19.8
1.7
1.6
72474
487
1.82
9.8
6.4
4.8
.04
21.1
11.8
4.3
4.0
.2
20.3
1.7
1.5
73174
145
1.92
10.8
6.2
5.4
.1
22.5
12.1
4.7
4.7
.4
21.9
1.8
1.7
81274
52
2.00
10.7
6.6
5.1
.1
22.5
12.2
5.1
5.5
.3
23.1
1.7
1.6
60275
85
2.89
16.9
9.2
8.7
.1
34.9
11.7
11.4
9.9
1.6
34.7
2.4
1.8
61675
415
3.39
18.5
10.4
8.8
.04
37.7
8.3
14.9
11.7
2.8
37.7
2.3
1.8
71075
106
3.41
20.1
9.0
8.9
.1
38.1
8.7
14.7
9.8
5.2
38.4
2.3
2.2
.9
.7
.8
.8
.6
.6
.5
.5
.5
102075 200 2.12 9.0 5.2 7.2 .2 21.6 4.3 8.8 6.6 1.1 20.8 2.7 1.7
.0
0.
-------
WATER ANALYSES, VACUUM EXTRACTORS, G25 (N) 1
K
Date Volume EC Ca Mg
Na
HCO 3
Cl
S0
NO 3
E
SAR
Ca/Mg
Cl Ratio
70374
180
5.27
26.7
21.8
9.0
.1
57.6
5.1
35.1
12.6
3.4
56.3
1.8
1.2
.07
71074
445
5.20
26.0
20.6
9.8
.1
56.4
9.9
32.2
9.4
5.0
56.5
2.0
1.3
.07
71774
225
4.89
24.0
18.0
9.5
.1
51.6
6.1
31.4
9.3
5.0
51.7
2.1
1.3
.08
72474
425
4.76
26.0
17.3
8.4
.1
51.8
6.8
29.6
10.8
4.9
52.1
1.8
1.5
.08
73174
308
4.78
24.8
16.9
8.8
.1
50.6
6.6
27.9
10.3
4.9
49.7
1.9
1.5
.08
81274
303
4.92
24.5
17.0
10.0
.1
51.6
6.9
28.3
11.2
5.5
51.9
2.2
1.4
.08
83074
291
4.75
24.1
18.2
8.6
.1
51.0
7.4
26.3
9.3
8.2
51.2
1.9
1.3
.09
101874
100
4.73
25.5
17.2
9.6
.1
52.4
7.1
26.5
12.1
8.0
53.7
2.1
1.5
.09
61675
228
5.66
28.8
20.3
13.6
.1
62.8
4.9
24.3
14.2
18.3
61.6
2.7
1.4
61975
90
5.66
29.7
19.3
13.9
.1
63.0
4.0
23.1
14.9
19.6
61.6
2.8
1.5
62675
75
5.57
31.6
20.0
13.2
.2
64.9
3.5
22.9
17.3
19.6
63.2
2.6
1.6
72375
75
5.38
28.7
21.5
13.7
.1
64.0
4.1
23.0
14.9
20.0
61.9
2.7
1.3
.0
I
80575
50 5.38 24.6 19.7 13.3 .2 57.5 3.6 24.8 13.6 15.3 57.2
-------
WA ER ANALYSES, VACUUM EXTRACTORS, C25 (middle) 2
Date Volume BC Ca
Mg
Na
K
E
HCO 3
Cl
S0 1
NO 3
E
SAR
Ca/Mg
Cl Ratio
62774
1076
4.25
19.4
7.2
18.4
.2
45.2
9.7
17.9
11.2
6.8
45.5
5.0
2.7
.13
70374
503
4.15
18.5
7.5
17.1
.2
43.2
9.9
14.9
10.1
7.9
42.8
4.7
2.5
.16
71074
280
4.34
20.3
8.9
19.4
.2
48.7
10.2
18.1
12.5
8.2
49.0
4.4
2.3
.13
71774
402
4.41
20.6
8.4
17.6
.2
46.8
10.7
19.3
11.2
7.2
48.4
4.6
2.4
.12
72474
276
4.45
21.6
8.6
18.2
.2
48.6
11.2
18.4
9.7
8.2
47.6
4.7
2.5
.13
73174
180
4.54
22.5
9.4
18.0
.2
50.1
11.1
19.1
10.6
7.6
48.3
4.5
2.4
.12
81274
4037
2.30
10.4
4.0
9.2
.1
23.7
7.6
6.9
6.7
3.6
24.8
3.4
2.6
.34
83074
1425
2.28
10.6
4.2
10.2
.1
25.2
10.0
6.1
5.4
4.3
25.8
3.8
2.5
.38
91874 -
150
1.89
9.0
3.5
8.3
.1
20.9
9.2
5.6
4.9
1.3
21.0
3.5
2.6
.42
92474
85
1.83
8.7
3.3
7.7
.1
19.8
9.1
5.7
4.5
.8
20.1
3.1
2.6
.41
101774
175
1.87
8.4
3.0
7.7
.1
19.2
9.4
5.5
3.5
.8
19.2
3.2
2.8
.42
61675
3919
2.37
10.3
5.3
10.5
.1
26.2
10.9
6.3
4.7
4.0
26.0
3.7
1.9
61975
167
2.41
9.7
5.9
11.2
.1
27.0
9.9
6.6
5.1
4.9
26.5
4.0
1.6
62675
127
2.68
13.9
6.4
10.6
.2
31.0
11.5
6.7
6.2
5.4
29.8
3.3
2.2
71075
214
2.69
13.8
5.2
10.7
.1
29.9
14.4
6.0
3.8
5.8
30.0
3.5
2.6
72375
500
2.92
15.5
7.6
11.1
.1
34.2
16.8
6.1
4.9
6.6
34.3
3.3
2.0
81175
185
2.96
16.3
7.4
11.4
.2
35.2
16.6
6.0
5.1
6.6
34.3
3.3
2.2
0
8-18-75
147 2.89 16.0 6.9 11.4 .2 34.5 16.7 5.6 5.0 5.8 33.2 3.4 2.3
-------
WATER ANALYSES, VACUUM EXTRACTORS, G25 (middle) 2
Date Volume EC Ca Mg Na K MOO 3 Cl SOk NO 3 E SAR Ca/Mg Cl Ratio
82575 488 2.88 15.3 6.8 11.2 .2 33.5 15.8 5.2 5.1 7.5 33.6 3.4 2.2
90275 1374 2.35 12.8 6.0 9.1 .2 28.0 15.1 4.7 4.2 28.8 3.0 2.2
90975 120 2.61 14.1 6.5 10.3 .2 31.0 18.3 5.0 3.5 4.9 31.6 3.2 2.2
91575 3930 2.44 13.2 4.7 8.8 .3 28.0 16.1 5.0 4.7 2.9 28.7 2.9 2.3
92375 120 2.43 13.4 5.9 9.2 .1 28.7 16.2 5.0 5.0 3.2 29.4 3.0 2.3
100275 65 2.13 10.7 6.1 9.3 .1 26.3 14.1 5.1 5.1 2.6 26.9 3.2 1.8
0
0
-------
WATER ANALYSES, VACUUM EXTRACTORS, 0-25 Cs) 3
Date Volume EC Ca Mg
Na
K
E+
R O 3
C l
S0i
NO 3
E
SAR
Ca/Mg
Cl Ratio
61774
713
2.94
15.3
7.7
7.9
.2
31.1
6.3
14.0
6.5
4.1
31.0
2.3
2.0
.17
61974
158
3.13
16.5
7.5
9.2
.2
33.4
6.9
14.8
6.1
4.8
32.7
2.7
2.2
.16
70374
486
3.33
16.8
8.5
8.7
.1
34.1
7.2
15.3
4.8
5.4
32.8
2.4
2.0
.15
71774
662
3.15
16.3
7.5
8.8
.1
32.6
7.3
14.4
5.0
6.2
32.8
2.5
2.2
.16
72474
518
3.10
16.4
6.9
8.1
.1
31.5
7.1
13.5
5.7
5.5
31.8
2.4
2.4
.17
73174
388
3.12
16.3
7.9
8.3
.1
32.6
7.1
13.7
6.1
5.5
32.4
2.4
2.1
.17
81274
121
3.05
15.7
7.8
8.3
.1
31.9
7.1
12.8
7.7
5.5
33.1
2.4
2.1
.18
83074
62
3.01
15.3
7.3
7.7
.1
30.4
7.5
12.6
5.2
6.7
31.9
2.3
2.1
.19
60275
75
3.19
17.7
8.2
9.7
.1
35.7
8.0
13.8
7.7
6.2
35.6
2.7
2.2
60575
58
4.32
23.5
12.2
12.0
.1
47.8
6.5
17.2
9.2
14.2
47.1
2.8
1.9
61675
1449
4.87
28.5
13.1
14.6
.1
56.3
6.3
16.2
9.9
23.7
56.2
3.2
2.2
61975
125
4.89
26.5
13.2
15.2
.1
55.0
6.3
15.6
10.0
23.7
55.6
3.4
2.0
62675
114
4.88
29.9
14.1
14.5
.1
58.6
6.7
15.4
11.1
23.7
57.0
3.1
2.1
72375
280
4.79
26.8
14.8
14.7
.1
56.4
8.0
14.6
9.6
21.9
54.2
3.2
1.8
80575
135
4.46
23.0
14.0
15.2
.1
52.3
7.4
13.7
7.9
24.6
53.5
0
-------
WATER ANALYSES, VACUUM EXTRACTORS, S-i
K
SO, NO 3 E SAR Ca/Mg Cl Ratio
Date
Volume
EC
Ca
Mg
Na
I
HC0
Ci
73173
1235
1.91
7.3
6.6
6.9
.1
20.9
10.6
8.6
1.8
.3
21.3
2.6
1.1
.27
70974
297
4.70
21.8
10.3
19.2
.2
51.4
8.1
28.0
6.8
6.7
49.7
4.8
2.1
.08
71774
205
4.87
22.8
9.8
18.3
.2
51.1
9.7
28.6
5.7
7.8
51.9
4.5
2.3
.08
72474
178
4.95
23.7
9.7
18.5
.2
52.1
10.6
27.7
6.3
7.9
52.4
4.5
2.4
.08
73174
149
5.18
25.2
10.0
19.2
.2
54.7
10.1
29.9
7.2
7.3
54.4
4.6
2.5
.08
80774
86
5.23
22.8
10.5
19.9
.2
53.4
6.6
31.4
7.4
7.8
53.4
4.9
2.2
.08
81574
38
5.46
21.2
11.8
23.0
.4
56.4
4.6
33.6
8.3
10.4
56.9
5.7
1.8
.07
82374
40
6.07
23.5
14.2
27.3
.3
65.3
4.0
39.8
8.5
12.7
65.0
6.3
1.7
.06
101674
440
7.74
42.2
17.6
24.1
.2
84.1
10.7
45.6
13.8
15.7
85.9
4.4
2.4
.05
102574
170
8.16
47.8
19.3
27.2
.3
94.5
9.6
52.0
13.6
22.1
97.3
4.7
2.5
.04
110174
380
6.13
36.4
14.3
21.9
.1
72.6
9.4
31.8
17.3
15.5
74.0
4.3
2.5
.07
52975
1400
7.61
46.3
19.4
24.3
.2
90.3
9.6
44.5
14.7
21.2
90.0
4.2
2.4
70175
90
10.90
62.9
28.6
38.9
.3
130.7
6.7
67.2
21.5
34.7
130.1
5.8
2.2
70875
307
8.21
50.2
18.4
30.3
.3
99.2
8.6
41.8
15.6
30.1
96.1
5.2
2.7
71475
700
7.24
45.0
15.7
25.4
.2
86.3
10.1
33.3
17.4
24.88
85.6
4.6
2.9
71875
400
6.97
42.8
18.4
25.3
.2
86.8
10.5
30.9
16.1
28.7
86.3
4.6
2.3
0
-------
WATER ANALYSES, VACUUM ZRACTOBS , S-i
Date Volume EC Ca Mg Na K HCO 3 Cl S0i NO 3 SAN Ca/Mg Ci Ratio
72875 1030 6.63 40.5 19.2 23.5 .2 83.4 12.4 29.0 17.1 21.9 80.3 4.3 2.1
80575 550 6.24 37.0 17.0 22.2 .2 76.3 12.8 26.2 17.9 17.4 74.3 4.3 2.2
81175 400 5.84 34.1 16.4 23.6 .2 74.2 12.6 24.0 17.5 16.6 70.7 4.7 2.1
81875 420 5.56 32.4 14.5 21.5 .2 68.5 13.5 20.6 17.0 17.4 68.4 4.4 2.2
82575 300 5.56 31.1 14.0 23.3 .2 68.6 15.8 19.5 16.3 17.8 69.4 4.9 2.2
90275 270 5.32 29.5 13.2 21.8 .2 64.7 16.7 18.1 15.5 15.4 65.6 4.7 2.2
90875 180 5.27 28.0 13.1 23.0 .2 64.0 17.2 18.9 14.6 13.3 64.1 5.0 2.1
91575 70 5.48 28.8 14.0 22.3 .2 65.2 15.6 19.2 16.5 16.8 68.1 4.8 2.1
92275 100 4.98 25.2 13.8 21.4 .2 61.1 6.4 18.4 19.4 16.8 61.0 4.8 1.9
92975 10* 4.94 14.6 16.8 29.1 .5 61.0 3.7 25.1 22.1 10.1* * 7.4 .9
100775 340 5.04 26.5 12.9 22.8 .2 62.4 17.1 18.8 14.0 12.4 62.4 5.1 2.1
*Imeufficient eample
-------
WATER ANALYSES, VACUUM EXTRACTORS, S2
Date Volume EC Ca Mg
SO NO 3 E SAR Ca/Mg Cl Ratio
Na
I C
E
HCO 3
Cl
73173
765
3.60
17.6
8.0
14.4
1.0
41.0
11.4
13.8
13.9
1.9
41.0
4.0
2.2
.17
80773
505
3.96
26.4
9.1
13.6
1.1
50.2
15.2
10.4
21.2
2.4
49.2
3.2
2.9
.23
81473
1175
4.04
27.4
10.9
11.9
.7
51.0
15.7
10.3
23.2
2.2
51.4
2.7
2.5
.23
82473
1770
32.2
13.2
16.3
16.4
11.6
29.9
2.6
60.6
3.4
2.4
.20
83173
2930
26.4
12.2
14.1
1.5
54.2
17.1
10.4
25.4
1.6
54.5
3.2
2.2
.22
92073
260
4.43
30.4
12.4
14.1
1.1
58.1
17.4
11.2
26.7
1.9
57.3
3.0
2.4
.21
113073
2735
3.67
13.8
13.2
14.0
.9
41.8
4.7
12.6
19.2
3.5
40.0
3.8
1.1
.19
121773
510
4.76
32.6
13.8
15.4
.8
62.3
13.8
14.4
30.0
4.5
63.3
3.2
2.4
.16
42774
4.98
32.8
14.2
15.6
.8
63.4
13.7
15.1
30.5
3.4
62.6
3.2
2.3
.16
61974
1820
5.08
33.1
14.5
14.9
.9
63.3
11.4
17.0
30.8
4.3
63.6
3.1
2.3
.14
70974
359
5.16
33.3
15.3
16.7
.9
66.2
10.9
17.7
30.1
5.0
63.8
3.4
2.2
.13
71774
27
5.27
27.7
15.9
18.2
1.0
62.8
4.7
20.5
32.0
6.4
63.6
3.9
1.7
.11
72474
28
5.38
28.0
16.7
19.0
1.2
64.9
4.6
20.8
37.6
3.6
66.4
4.0
1.7
.11
81574
2590
3.13
14.1
9.6
12.1
.8
36.6
5.4
10.0
17.0
3.6
36.0
3.5
1.4
.24
82374
530
3.72
15.8
12.6
13.8
.9
43.0
3.3
12.4
20.6
5.0
41.3
3.7
1.2
.19
93074
316
4.86
19.1
17.0
19.6
1.1
56.8
3.3
17.4
29.9
6.5
57.1
4.6
1.2
.13
100574
800
4.71
20.1
16.6
18.5
.9
56.0
3.1
17.1
28.7
5.0
53.9
4.3
1.2
.14
101674
1440
4.80
21.9
17.9
19.0
.8
59.7
2.5
19.2
3q.6
.8
6 1
3
1.2
.12
I-
L.1
-------
WATER ANALYSES, VACUUM EXTRACTORS, S-2
Date Volume EC Ca Mg
K
SOi NO 3 £ SAR Ca/Mg Cl Ratio
.11
.11
Na
E+
Hc0 3
Cl
102574
500
4.84
23.4
16.6
18.1
.9
59.0
2.3
20.9
29.2
5.1
57.4
4.0
1.4
110174
360
4.83
22.4
14.9
18.5
.7
56.4
4.2
20.8
27.0
5.3
57.2
4.3
1.5
52975
600
4.88
24.0
16.7
19.1
.8
60.6
3.8
22.8
32.7
3.8
63.1
4.2
1.4
60375
149
5.0)
24.6
17.3
20.1
.8
63.0
4.4
22.8
33.8
3.8
64.8
4.4
1.4
60575
1200
4.9)
23.3
16.9
19.8
.8
60.8
3.4
23.6
32.1
3.4
62.4
4.4
1.4
61675
350
5.15
21.4
18.2
22.1
.7
62.4
3.1
25.5
32.5
.1
61.2
5.0
1.2
62475
220
5.3)
22.3
19.6
22.4
.9
65.2
2.5
26.9
32.5
3.3
65.2
4.9
1.1
70175
80
5.64
24.2
17.5
26.0
1.0
68.7
2.5
27.9
34.4
3.9
68.7
5.7
1.4
70875
208
5.23
23.1
16.0
22.7
.9
62.7
2.7
26.1
30.6
4.4
63.7
5.1
1.4
71475
250
5.00
21.6
15.2
21.7
.9
59.4
2.8
25.2
29.6
4.2
61.8
5.1
1.4
71875
250
5.02
21.2
15.2
21.9
.9
59.1
2.7
25.2
28.9
4.2
61.1
5.1
1.4
72875
740
4.86
20.1
20.9
20.7
.9
62.6
2.6
24.1
31.0
4.0
61.7
4.6
1.0
80575
410
4.84
19.8
20.8
21.6
.9
63.0
2.8
24.8
31.0
3.7
62.3
4.8
1.0
81175
250
4.89
20.0
20.1
22.2
.9
63.1
2.5
24.2
30.8
3.7
61.2
5.0
1.0
81875
270
4.97
19.8
19.1
22.1
.9
61.9
2.6
23.9
32.5
4.2
63.1
5.0
1.0
82575
170
5.15
19.1
19.0
23.6
.9
62.6
3.0
24.3
31.7
5.6
64.7
5.4
1.0
90275
460
5.11
18.8
18.9
23.6
.8
62.2
3.3
24.2
29.4
5.6
62.5
5.4
1.0
90875
430 5.02 18.6 18.9 23.0 .9 61.4
3.0 24.9 28.9 4.2 61.0 5.3 1.0
-------
WATER ANALYSES, VACUUM EXTRACTORS, S-2
Date
Volume
EC
Ca
Mg
Na
K
E 4
HCO 3
Cl
SO ,
NO 3
E
SAR
Ca/Mg Cl Ratio
91575
300
5.16
19.1
18.7
23.2
.9
61.9
2.7
24.4
32.1
3.6
62.8
5.3
1.0
92275
250
5.20
20.8
18.4
23.4
.8
63.3
2.8
24.2
33.3
3.4
63.7
5.3
1.1
92975
45
5.27
21.4
20.0
22.9
.9
65.2
4.5
21.6
33.7
4.6
64.5
5.0
1.1
100775
760
5.14
19.6
20.0
22.7
.9
63.2
2.5
24.9
33.9
3.8
65.2
5.1
1.0
102275
290
5.20
21.0
19.6
21.7
.8
63.1
2.9
26.3
32.0
1.1
62.4
4.8
1.1
I - .
0
U
-------
WA1 ER ANALYSES, VACUUM EXTRACTORS, S-3
Date Volume EC Ca Mg Na
SO 4 NO 3 £ SAN Ca/Mg Cl Ratio
K
£1
Rc0 3
Cl
73173
370
6.17
21.0
13.0
32.2
.6
66.8
13.8
30.5
17.1
3.6
65.0
7.8
1.6
80773
320
6.22
20.3
13.9
39.5
1.4
75.1
14.2
30.5
29.7
3.8
78.2
9.5
1.5
81473
785
6.28
22.1
13.3
36.5
1.3
73.3
13.9
29.7
28.6
3.5
75.8
8.7
1.7
82473
3010
26.0
15.0
43.5
16.1
30.4
30.6
3.1
80.2
1.7
83173
685
17.8
14.8
40.8
1.9
75.3
21.5
25.8
26.8
2.2
76.3
1.2
91173
1190
6.87
24.8
14.8
47.4
1.3
88.3
24.9
26.3
33.5
3.4
88.2
11.0
1.7
92073
425
7.11
24.5
16.3
50.8
1.3
92.8
25.5
27.2
33.0
3.5
89.2
11.0
1.5
113073
853
6.00
13.9
12.6
42.7
1.0
70.1
15.6
23.6
25.9
5.0
70.1
12.0
1.1
121773
390
6.25
17.8
12.5
45.5
.8
76.6
20.0
23.9
25.6
6.2
75.8
12.0
1.4
42774
5.63
7.6
9.3
42.4
.9
60.1
12.2
20.3
22.9
6.7
62.0
15.0
.8
60574
870
5.59
13.2
8.3
41.9
.6
63.9
14.4
19.3
21.3
7.4
62.3
13.0
1.6
100574
480
5.59
13.0
8.5
43.4
1.0
65.9
19.2
18.1
19.8
9.0
66.1
13.0
1.5
101674
77
5.67
10.9
10.8
40.3
1.0
62.4
12.9
21.9
17.3
10.0
62.1
12.0
1.0
110174
1840
5.24
13.3
8.2
37.9
.8
60.2
19.8
16.1
15.0
10.4
61.3
12.0
1.6
111574
1550
4.96
7.3
8.8
40.9
.8
57.9
13.4
17.4
15.5
10.8
57.1
14.0
.8
52975
60375
150
184
5.47
5.25
12.3
8.6
9.2
10.7
42.9
41.9 -
.9
.9
65.3
62.1
17.5
13.9
19.1
19.0
18.1
17.0
9.2
11.4
64.0
61.2
13.0
13.0
1.3
.8
.08
.08
.08
.08
.09
.09
.09
.10
.10
.12
.12
.13
.11
.14
.13
-------
WATER M4ALYSES, VACUUM EXTRACTORS, S-3
I-
C
Date
Volume
EC
Ca
Mg
Na
K
E+
HCO 3 Cl
S 0 i
NO 3
E
SAR
Ca/Mg Cl Ratio
62475
780
5.59
5.4
9.8
46.7
.9
62.8
12.1 21.1
18.0
9.3
60.6
17.0
.5
70875
325
6.89
11.9
13.7
54.4
1.1
81.1
14.1 28.3
21.2
17.0
80.6
15.0
.9
71475
540
6.98
14.3
13.2
54.2
1.1
82.8
13.5 28.1
21.6
17.8
81.0
15.0
1.1
71875
1180
6.86
13.0
12.9
53.6
1.0
80.6
11.4 28.3
21.6
18.7
80.0
15.0
1.0
72875
2120
6.82
12.5
18.1
52.3
1.0
83.9
10.1 28.6
26.9
16.6
82.2
13.0
.7
80575
2150
6.54
9.8
17.5
51.8
1.3
80.4
8.2 28.4
24.7
17.4
78.6
81175
630
6.63
11.8
17.0
52.3
1.0
82.1
9.6 27.4
28.8
15.8
81.7
14.0
.7
81875
1180
6.62
12.8
16.1
53.0
1.0
82.9
12.2 27.0
29.4
11.5
80.0
14.0
.8
82575
1380
6.54
10.5
15.8
56.3
1.0
83.5
12.6 25.6
29.4
13.3
80.8
16.0
.7
90275
1480
6.28
9.8
15.6
50.6
1.0
77.0
12.5 25.8
28.0
10.0
76.2
14.0
.6
90875
810
5.85
7.7
14.7
49.0
1.0
72.4
11.5 23.8
26.5
8.7
70.4
15.0
.5
91575
370
5.91
8.8
14.8
46.0
.9
70.5
11.3 22.4
31.2
8.6
73.6
13.0
.6
92275
1820
5.77
9.1
14.6
45.2
.8
69.8
13.4 21.2
25.0
8.6
68.2
13.0
.6
92975
30
5.70
6.0
15.0
44.4
.8
66.2
9.2 22.3
28.8
6.8
67.0
14.0
.4
100775
3930
5.44
10.5
13.9
39.2
.8
64.4
16.0 - 18.8
26.0
5.6
66.4
11.0
.7
102275
170
-------
WATER ANALYSES, VACUUM EXTRACTORS, S-4
Date Volume EC Ca Mg
1.74
K SO 4 NO 3 E SAX Ca/Mg Cl Ratio
.2 19.9
HCO 3
10.2
13.7
13.0
9.3
8.3
14.8
.4 19.7 2.1
Cl
6.7
12.8
16.7
18.9
21.7
20.7
Na
73173
1084
9.6
4.5
5.7
2.3
2.1
.35
82473
220
18.0
8.2
10.0
5.8
2.2
.18
91173
140
3.40
11.9
10.7
12.5
.3
35.4
6.2
.7
36.6
3.7
1.1
.14
42774
3.73
13.2
13.6
13.5
.2
40.5
10.2
3.2
41.6
3.7
1.0
.12
6-0574
630
4.30
19.7
11.2
16.1
.2
47.3
11.9
4.3
46.2
4.1
1.8
.11
101674
62
4.60
23.7
12.2
17.1
.3
53.2
12.5
5.0
53.0
4.0
1.9
.11
102574
20
110174
350
5.17
26.4
11.6
21.5
.1
59.6
9.1
22.0
18.7
10.8
60.6
4.9
2.3
.11
111574
980
4.46
23.7
11.9
17.8
.3
53.7
15.1
20.3
10.6
5.5
51.4
4.2
2.0
.12
52975
126
4.86
26.2
13.6
18.0
.3
58.1
8.1
26.4
14.5
7.2
56.2
4.0
1.9
60375
267
4.44
23.2
13.2
17.6
.3
54.3
15.0
20.7
13.5
5.0
54.3
4.1
1.8
60575
190
4.50
23.5
13.7
17.9
.3
55.4
15.4
20.4
15.2
4.6
55.7
4.2
1.7
60775
1030
4.33
22.4
12.2
16.4
.3
51.3
13.8
20.3
13.8
4.3
52.1
3.5
1.8
61675
2740
4.52
23.3
12.8
18.2
.3
54.7
15.6
19.9
14.8
3.7
53.9
4.3
1.8
62475
100
5.06
21.6
15.0
22.9
.4
60.0
9.9
25.7
17.9
6.3
59.8
5.4
1.4
70175
40
4.88
21.2
14.0
21.3
.4
56.9
7.5
25.3
18.7
4.7
56.2
5.1
1.5
70875
58
4.97
23.4
13.3
22.4
.4
59.5
13.4
23.6
16.2
6.0
59.2
5.2
1.8
71575
260
4.77
25.3
11.8
20.5
.3
57.9
17.2
20.6
15.5
5.4
58.7
4.8
2.1
-------
WATER ANALYSES, VACUUM EXTRACTORS, 5-4
Date
Volume
EC
Ca
Mg
Na
K
E+
HCO 3
Cl
S0 1
NO 3
E
SAR
Ca/Mg Cl Ratio
72875
250
4.59
24.1
15.7
20.5
.3
60.6
20.7
19.1
16.0
4.7
60.5
4.6
1.5
92275
170
2.77
13.0
6.7
11.8
.2
31.8
15.6
6.5
6.3
3.5
32.0
3.8
1.9
100775
455
4.99
25.4
15.5
20.7
.3
61.8
20.4
20.8
19.3
3.8
64.2
4.6
1.6
102275
150
4.76
18.6
16.7
21.6
.3
57.2
11.7
23.7
20.2
.9
56.5
5.1
1.1
I-
0
-------
WATER ANALYSES, VACUUM EXTRACTORS, S-5
Date Volume EC Ca Mg
SOS , NO 3 E SAR Ca/Mg Cl Ratio
.66
.69
.68
Na
K
Z+
HCO 3
Cl
73173
1520
1.66
12.3
3.4
3.8
Tr
19.5
6.6
3.5
8.2
.6
19.0
1.4
3.7
80773
2270
1.65
11.4
3.1
3.7
.1
18.3
6.6
3.4
8.2
.6
18.8
1.4
3.7
81473
48
1.64
10.4
3.1
4.4
.1
18.0
7.2
3.5
7.1
.4
18.2
1.7
3.4
70175
1000
2.84
15.7
5.9
11.5
.2
33.3
11.8
9.4
8.8
3.2
33.2
3.5
2.7
70875
933
2.95
15.4
6.4
11.8
.2
33.8
13.7
9.6
7.4
2.8
33.5
3.6
2.4
71475
1140
2.79
15.2
6.2
11.0
.2
32.7
15.0
8.3
7.5
2.0
32.8
3.4
2.4
71875
440
2.84
15.6
8.4
11.2
.2
35.4
16.4
8.2
8.3
2.1
35.0
3.2
1.8
72875
1450
2.48
14.1
8.0
9.1
.2
31.4
17.6
6.1
6.0
1.1
30.8
2.7
1.8
80575
500
2.57
14.8
8.5
9.6
.2
33.2
19.9
6.3
7.0
.4
33.6
2.8
1.7
81175
1360
2.36
13.6
7.3
8.7
.2
29.8
17.1
5.6
6.5
.5
29.6
2.7
1.9
8-18-75
520
2.58
14.5
7.7
9.6
.2
32.0
18.7
6.2
7.2
.4
32.4
2.9
1.9
82575
820
2.57
13.9
7.5
8.9
.2
30.6
16.1
6.5
6.7
.3
29.5
2.7
1.9
90275
530
2.39
11.5
7.5
9.1
.2
28.3
17.7
6.3
7.9
.7
32.6
90875
660
2.54
14.0
8.1
9.8
.2
32.1
18.0
6.8
10.4
.5
35.7
91575
530
2.58
15.7
7.2
9.2
.2
32.3
18.2
6.7
8.3
.05
33.2
3.0
2.2
92275
260
2.64
14.3
7.2
9.5
.2
31.2
18.1
6.8
7.3
.1
32.3
2.9
2.0
I - .
I-.
92975
55 2.18 7.9 7.4 9.4 .2 24.9 10.5 6.8 7.2
.4 25.0 3.4 1.1
-------
WATER ANAL, VACUUM EXTRACTORS, S-5
Date
Volume
EC
Ca
Mg
Na
K
HCO 3
Cl
S0
NO 3
E
SAR
Ca/Mg Cl Ratio
100775
1855
2.61
15.1
7.2
8.8
.2
31.3
17.4
6.8
7.6
.4
32.2
2.7
2.1
102275
120
2.20
5.6
8.0
9.8
.2
23.6
8.1
7.5
8.4
.1
24.1
3.7
.7
I - .
I - .
-------
WAXER INALYSES, VACUUM EXTRACTORS, S-6
SO, NO 3 £ SAR Ca/Mg Cl Ratio
Date Vo1 e BC Ca Mg
73173 290 2.54 12.0 6.8 6.6 .7 28.1 2.8 1.8 .19
42774 7.43 36.8 25.0 28.2 13.6 87.0 5.0 1.5 .06
60574 680 8.88 49.6 33.0 40.8 17.4 111.2 4.8 1.4 .05
61274 612 7.57 40.5 20.8 26.6 17.4 87.5 5.2 2.0 .07
61974 280 7.83 43.2 24.9 28.1 21.5 92.4 4.9 1.7 .07
70974 309 8.33 42.0 27.7 28.9 23.5 98.2 5.1 1.5 .07
71774 104 7.86 39.4 27.2 27.3 26.2 99.0 5.2 1.4 .07
72474 119 7.82 38.6 23.7 23.4 21.9 92.0 5.2 1.6 .08
73174 72 8.45 43.8 26.9 31.4 22.8 102.0 5.4 1.6 .07
100574 1920 12.10 59.1 40.7 40.6 37.3 139.4 5.6 1.4 .05
101674 1460 12.60 61.6 42.5 45.4 40.5 147.1 5.6 1.4 .05
102474 1790 10.60 56.5 37.5 42.9 40.1 137.2 6.3 1.5 .06
110274 1020 11.00 58.6 40.8 43.5 43.4 143.1 6.2 1.4 .06
111574 430 8.98 49.2 35.4 44.8 27.4 119.4 5.8 1.4 .07
52975 840 9.25 53.5 35.9 50.8 28.9 129.2 5.9 1.5
6_03_75* 3165 7.24 39.5 36.7 40.6 25.4 115.3
60575 56 9.59 53.2 37.2 40.9 .2 131.5 16.9 36.7 53.6- 27.7 134.9 6.1 1.4
Na
8.6
27.6
30.9
28.7
28.6
30.2
30.2
28.7
32 1
39 5
40.7
43.3
44 1
37.7
39.3
37 0
K
.2 27.6
.2 89.6
.2 113.7
.2 90.2
.1 96.7
.3 100.2
.3 97.0
.2 91.2
.3 103.1
.2 139.5
.2 144.9
.2 137.4
.2 143.6
.2 122.5
.2 128.9
.2 115.4
Boo 3
8.3
8.8
9.6
8.6
9.4
11.3
13.3
15.8
13 5
14 5
14.4
13 4
13.4
13.2
14.0
14 3
Cl
12.5
36.3
43 4
34 8
33.4
34.5
32.2
30 9
34 3
47 1
46.9
40.8
42 8
34.0
35.4
35 0
*Not USSL data
-------
WATER ANALYSES, VACUUM EXTRACTORS, S-6
Date Volume EC Ca Mg
Cl Ratio
Na
K
E
HCO 3
Cl
S0 1
NO 3
E
SAR
Ca/Mg
61675
730
8.16
42.4
30.8
39.8
.2
113.1
18.6
28.3
45.8
26.3
113.0
6.6
1.4
62475
200
8.34
39.3
34.4
42.9
.2
116.8
16.6
29.2
53.3
16.2
115.3
7.1
1.1
70175
20
8.87
37.6
36.1
51.6
.2
125.5
7.0
35.8
60.9
18.7
122.4
8.5
1.1
70875
574
7.70
39.6
25.7
38.2
.2
103.7
19.3
25.3
44.3
13.3
102.3
6.7
1.5
71475
1620
7.17
38.5
23.2
36.4
.2
98.3
20.0
22.8
43.0
11.6
97.3
6.5
1.7
71875
770
6.98
36.6
23.2
35.1
.2
95.2
19.3
21.8
44.4
9.6
95.2
6.4
1.6
72875
1480
6.43
33.7
27.2
31.3
.2
92.3
21.8
20.1
41.8
8.6
92.2
5.7
1.2
81175
900
5.88
30.6
24.8
31.9
.2
87.6
23.2
17.1
38.5
6.8
85.6
6.1
1.2
81875
950
5.68
28.5
21.9
29.4
.1
79.9
23.5
15.8
35.9
4.6
79.8
5.9
1.3
82575
1040
5.43
25.9
19.6
30.6
.1
76.2
26.0
14.4
31.2
4.2
75.8
6.4
1.3
90275
2840
4.01
19.9
15.0
23.4
.2
58.6
22.5
11.0
21.9
3.2
58.5
5.6
1.3
90875
2430
4.07
18.6
14.8
20.9
.1
54.4
22.2
10.3
20.0
1.8
54.4
5.1
1.2
91575
1180
4.30
19.9
15.3
21.5
.1
56.8
21.7
10.2
23.0
1.2
56.2
5.1
1.3
92275
1000
4.44
21.0
17.3
21.6
.1
60.0
22.4
10.4
26.2
1.8
60.8
4.9
1.2
92975
45
4.28
19.3
16.8
21.5
.1
57.7
20.3
10.7
27.2
1.5
59.6
5.1
1.1
100775
3920
3.83
18.5
14.3
17.4
.1
50.2
19.4
9.1
20.9
1.0
50.4
4.3
1.3
102275
140
3.57
10.5
14.6
18.4
.1
43.6
9.7
9.5
22.7
.2
42.1
5.2
.7
I-
-------
TABLE A2
DRILL HOLE WATER LEVEL DATA, LITTLE SALT WASH-ADOBE WASH AREA OF THE GRAND VALLEY, 1974-1975
I-I
I - .
8 9 10
S S S
Hole__________________________________________
Date
1
2
3
hA
11B
S
12
13
15
Water
Level
(feet)
8/23/74
5.5
11.5
9/12/74
12.0
21.0
16.0
14.0
17.0
11.5
7.0
10.5
9.0
10/31/74*
6.0
10.0
6.4
21.6
17.8
14.8
10.7
11.8
7.2
6.4
7.6
12/5/74
8.5
12.0
7.0
22.9
17.0
11.0
12.5
7.5
7.0
8.0
12/17/74
1/23/75
1/31/75
2/14/75
8.6
8.6
dry
dry
11.3
12.7
8.6
12.0
8.4
4/15/75
9.1
12.8
7.9
dry
dry
15.7
11.5
13.1
4.7
12.0
9.2
4/25/75**
12.5
6.0
dry
dry
15.7
11.2
12.8
4.9
12.8
4/30/75
12.3
5.9
dry
dry
15.2
11.2
12.8
7.1
11.6
5/2/75
4.5
5.4
dry
dry
16.8
11.2
12.6
12.].
11.6
5/20/75
2.5
10.3
5.4
dry
dry
14.6
10.7
12.0
6.3
10.9
8.5
6/4/75
4.1
10.0
5.4
dry
21.5
13.8
10.6
4.7
6.3
10.6
8.4
6/25/75
2.7
9.6
5.4
dry
20.8
14.4
10.6
12.3
8.7
10.2
8.2
8/7/75
2.7
9.2
6.2
23.1
18.7
13.5
15.7
12.4
5.9
10.5
7.5
9/4/75
3.5
9.4
6.2
21.9
17.7
14.0
10.6
12.2
7.8
10.9
7.3
10/9/75
4.0
9.5
22.2
17.0
14.3
10.4
11.5
6.9
11.1
7.0
11/18/75
7.8
10.5
8.5
dry
dry
11.3
12.5
7.0
12.0
7.0
12/17/75
dry
9.1
8.5
dry
D
16.0
10.5
12.5
7.5
11.2
6.5
1/12/76
8.0
17.5
8.7
D
D
17.0
17.0
18.5
7.5
13.0
8.5
2/17/76
8.5
12.2
9.0
D
D
16.5
11.5
13.0
6.5
12.0
8.5
3/15/76
9.5
13.3
9.0
D
D
17.5
11.5
11.0
7.0
13.0
7.0
4/19/76
6.5
12.0
6.0
D
D
16.0
11.0
13.0
7.0
12.2
8.5
-------
DRILL HOLE WATER LEVEL DATA, LITTLE SALT WASHADOBE WASH AREA OF THE GRAND VALLEY, 19741975
Hole___________________________________________
Date
16
17
18A
18B 19i 192
20i
202
21
22i
222
Water Level (feet)
8/23/74
9/12/74
4.0
7.0
10/31/74*
3.6
12.2
12/5/74
7.5
15.0
12/17/74
10.1
17.3 3.8 3.8
7.0
7.0
9.0
6.0
6.0
1/23/75
19.0 6.0
8.8
10.8
7.0
1/31/75
10.8
18.3 6.0 5.2
8.8
8.8
10.7
7.0
7.0
2/14/75
9.1
15.6
11.0
15.3 5.7 5.8
8.9
9.9
10.6
6.8
6.8
4/15/75
9.5
15.7
11.7
19.4 6.9 5.6
10.0
10.0
11.0
7.3
7.6
4/25/75**
7.1
15.7
4/30/75
5.8
15.7
5/2/75
6.5
15.9
6.7 5.3
10.1
10.1
10.7
5/20/75
3.5
14.9
11.8
12.0 4.3 3.3
9.0
9.0
9.7
4.5
4.5
6/4/75
3.5
14.8
11.9
17.5 4.0 3.5
6.1
6.8
10.0
4.3
4.2
6/25/75
3.6
14.2
11.9
175 4.0 3.8
6.9
6.8
10.7
4.2
4.4
8/7/75
3.3
11.8
12.0
16.3 2.9 3.3
4.6
4.7
11.2
4.0
4.0
9/4/75
3.2
12.0
12.2
15.8 2.8 3.2
5.2
5.2
10.8
3.5
3.5
10/9/75
3.2
12.1
13.6
16.6 3.4 3.3
6.9
6.6
11.0
3.9
4.0
11/18/75
6.5
22.0
13.5
17.5 4.5 3.8
7.5
7.5
11.5
5.0
4.5
12/17/75
8.0
D
11.0
18.0 4.8 4.5
8.5
8.0
11.0
6.5
5.5
1/12/76
8.5
D
13.0
20.0 6.0 6.0
11.0
10.0
11.5
7.0
7.0
2/17/76
9.5
D
18.5
13.0 6.2 6.3
10.0
9.5
11.0
7.5
6.5
3/15/76
10.0
D
19.0
14.0
10.0
6.0
12.0
7.0
4.0
4/19/76
5.0
D
19.5
13.0 5.0 5.0
10.0
10.0
11.3
7.0
7.0
out October 14, 1974
Highline Canal turned
Highilne Canal turned in April 14, 1975 (at Little Salt Wash 0700, April 15)
s indicates drill holes in which artesian water zone was encountered in Mancos
Subscripts 1 and 2 indicate drill holes in which two different lengths of PVC casing
were placed.
*Goverjm ent
** (Jvernment
I -I
U I
Subscript
Shale.
-------
TABLE A3
*H, 1 casing, deep
L, 4 casing, shallow
WATER SAMPLES, ARS WELLS (SCHNEIDER), 6/25/75, GRAND JUNCTION, COLORADO
Well
No.
pH
EC
K
HCO 3
Cl
NO 3
SOz,
Ca
Mg
Na
1
7.85
0.74
2.72
0.81
2.61
.087
3.70
1.94
.138
0.91
2
7.76
7.63
14.97
24.18
78.26
.407
10.70
15.72
1.135
86.25
3
7.51
3.14
5.99
4.93
23.77
.299
12.76
3.88
.184
20.50
9
7.97
3.35
24.50
8.55
6.09
.371
3.70
3.70
.531
34.25
10
7.56
3.91
24.16
11.82
10.87
.412
6.10
5.96
.330
36.25
hA
7.53
4.35
14.29
11.82
23.91
.274
9.00
10.32
.789
27.81
liE
7.56
5.24
18.21
13.86
29.13
.220
8.10
10.42
.700
45.50
12
7.91
18.50
13.97
49.34
379.35
.621
23.00
33.04
.795
365.63
13
7.40
4.69
15.97
14.88
23.77
.384
3.76
9.92
.375
41.87
15
7.65
15.90
17.30
117.19
189.13
.767
18.60
23.04
35.47
235.94
16
7.75
3.54
5.65
7.40
26.27
.203
14.36
.72
.263
18.75
17
7.51
3.86
13.97
17.27
16.26
.217
7.20
5.98
.145
37.19
18_H*
7.88
3.93
18.06
16.81
16.89
.353
6.40
5.44
.199
40.50
18L
7.59
5.53
9.65
13.16
46.29
.849
10.80
6.64
.795
50.63
19H
7.67
5.24
11.98
14.39
38.16
19L
11.15
5.37
25.17
0.02
32.17
.481
3.80
11.52
.821
41.12
20H
7.53
5.06
20.41
12.84
26.96
.281
9.20
21.52
.854
27.81
20L
757
4.81
18.46
13.65
25.43
.286
9.00
19.24
.758
25.62
21
7.69
1.92
6.24
4.07
7.83
.136
5.00
3.30
.222
9.50
22H
7.22
5.40
13.31
21.13
33.78
.361
3.90
7.80
2.224
56.25
22L
7.18
4.77
14.64
14.39
26.27
.299
2.40
7.42
.422
42.37
a
-------
WATER SAMPLES FROM ARS WELLS (SCHNEIDER), 8/7/75, GRAND JUNCTION
/ 1
Well No. pH EC Ca Mg Na K HCO 3 Cl NO 3 SOt pCaSOz,
1 7.44 1.15 5.49 3.29 3.26 .084 6.70 2.27 .158 6.42 5.68
2 7.82 8.12 15.47 32.90 95.65 .537 13.50 19.90 1.443 111.74 4.73
3 7.74 3.05 7.73 10.69 20.43 .488 15.00 5.10 1.722 17.05 5.39
9 7.28 3.08 17.47 16.45 6.09 .276 3.80 3.28 .173 35.51 4.81
10 7.57 3.26 18.46 16.04 11.09 .355 7.50 5.30 .206 33.14 4.83
hA 7.74 3.68 11.48 12.34 24.56 .243 8.30 9.96 .419 28.12 5.08
11B 7.64 4.49 16.47 13.98 29.57 .174 8.70 10.52 .522 44.24 5.21
12 7.89 18.42 13.97 50.16 373.91 .660 23.00 30.66 .438 406.96 4.66
13 7.64 3.87 16.97 14.80 17.61 .338 4.40 9.04 .206 37.88 4.83
15 7.65 14.52 16.97 119.24 208.70 .794 18.40 21.56 34.775 280.97 4.62
16 7.82 4.29 6.49 9.87 38.48 .315 17.80 10.54 .236 26.99 5.36
17 7.58 3.03 10.98 12.34 13.91 .230 9.40 5.34 .166 24.62 5.11
18_L* 7.76 5.11 10.48 13.16 43.70 .852 11.80 6.86 .623 49.72 5.00
18H 7.29 3.53 14.72 14.39 15.22 .445 5.80 4.80 .478 36.46 4.89
19H 7.57 4.82 12.48 14.80 35.87 .514 4.40 10.54 .307 50.89 4.90
19L 8.64 4.16 15.22 1.64 29.56 .488 1.00 11.10 .401 38.35 4.84
20H 7.63 4.46 16.22 12.58 27.30 .269 9.10 21.36 .438 27.70 4.98
20L 7.71 4.21 13.67 12.50 23.70 .269 8.40 19.30 .623 24.72 5.07
21 7.84 1.58 5.49 4.11 6.74 .107 5.80 4.40 .145 9.38 5.58
22H 7.32 4.23 15.97 17.60 23.70 .371 4.50 7.62 .236 47.73 4.81
22L 7.20 4.32 17.02 14.80 26.87 .371 3.30 8.34 .189 48.77 4.77
*H, 1 casing, deep
L, 4 casing, shallow
-------
WATER SAMPLES FROM ARS WELLS (SCHNEIDER), 10/12/75, GRAND JUNCTION
Well me/i_______________________________________
No. pH EC Ca Mg Na K HCO 3 Cl NO 3 SO 4 pCaSO
1 7.18 2.70 13.42 6.77 11.03 .21 6.80 5.18 .257 19.81 5.06
2 7.82 12.61 22.50 55.89 167.83 .80 19.60 26.00 1.39 200.31 4.53
3 7.75 1.64 5.61 3.27 7.90 .27 5.50 4.86 .267 8.13 5.63
9 7.54 3.84 21.49 22.80 11.03 .43 3.50 3.98 .824 44.62 4.71
10 7.50 3.55 24.26 13.35 9.77 .42 7.20 5.34 .354 33.14 4.73
hA 7.48 3.93 14.94 13.14 23.55 .29 9.20 9.88 .622 28.54 4.98
11B 7.71 4.85 19.54 14.38 32.12 .19 7.80 10.38 .702 45.70 4.76
12 7.83 21.28 18.28 53.41 456.30 .82 23.40 32.84 .647 463.75 4.54
13 7.59 4.18 19.78 14.38 20.53 .41 3.40 8.84 .416 43.24 4.74
15 7.69 16.19 20.11 122.29 228.15 .97 18.40 22.00 36.26 282.19 4.56
16 7.73 4.23 9.14 10.88 36.07 .33 17.60 10.46 .451 24.41 5.26
17 7.44 3.78 19.72 17.25 12.28 .30 10.30 9.64 .340 29.00 4.88
l8 H* 7.54 &.O4 21.99 17.87 17.29 .33 6.40 5.90 .257 43.70 4.71
18L 7.86 5.48 14.18 14.58 49.22 1.02 12.36 6.88 .824 57.81 4.85
19L 7.77 3.80 16.95 11.91 21.67 .20 6.96 8.36 .400 32.68 4.88
19H 7.69 1.29 4.35 2.66 6.02 .28 3.80 3.96 .218 6.82 5.75
20 i. 7.68 4.26 16.95 11.50 24.80 .25 10.20 18.36 .893 23.03 5.02
20H 7.64 4.21 16.70 11.29 24.80 .24 10.00 17.82 .893 22.11 5.03
21 7.79 1.59 6.11 3.89 6.02 .13 5.36 3.30 .186 8.81 5.56
22L 7.24 4.63 20.22 16.23 27.30 .36 4.60 7.78 .340 47.84 4.72
22H 7.48 1.19 3.59 1.83 5.39 .27 3.80 3.86 .201 5.68 5.87
*H, 1 casing, deep
L, 4 casing, shallow
-------
WATER SAMPLES FROM ARS WELLS (SCRNEIDER), 11/18175, GRAND JIJNCTION
Well
No.
pH
EC
me
/1
Ca
Mg
Na
K
HCO 3
Cl
NO 3
SO 4
pCaSO 4
1
7.60
1.50
3.84
3.62
6.35
.22
5.90
4.06
.16
7.05
5.82
2
7.35
12.52
17.13
53.27
155.22
.73
18.10
24.42
1.87
165.13
4.68
3
7.17
2.07
6.65
5.87
9.88
.23
7.30
4.36
.42
14.12
5.41
10
6.98
4.19
20.37
13.93
17.33
.45
7.50
4.88
.45
39.42
4.76
hA
6.75
4.10
11.89
12.93
25.76
.29
9.20
9.40
.81
28.86
5.07
1 1B
7.08
5.08
18.62
15.75
31.59
.20
7.80
9.62
.87
45.39
4.79
12
7.44
20.49
15.88
45.68
388.04
.81
21.00
28.58
1.37
371.03
4.63
13
6.64
4.32
19.37
15.75
18.30
.33
3.20
7.82
.42
39.88
4.78
16
7.14
3.66
6.15
10.11
27.70
.32
17.00
8.60
.48
15.79
5.54
17
7.47
3.21
14.82
14.31
11.09
.26
7.30
5.10
.15
24.66
5.00
1811*
6.97
4.30
18.87
18.36
18.30
.36
6.50
4.88
.40
40.80
4.79
l8L
7.40
6.71
13.63
20.09
59.52
.98
12.70
7.38
2.94
62.43
4.88
19H
7.06
5.39
14.63
15.83
39.70
.53
3.80
9.50
.71
52.46
4.85
19L
7.32
4.02
14.63
12.32
23.49
.25
7.00
7.70
.57
32.99
4.94
20H
7.02
4.52
13.38
12.12
27.37
.29
9.40
17.74
1.04
23.34
5.11
21
7.34
1.79
6.40
4.26
7.29
.16
5.00
2.54
.35
12.87
5.42
22H
6.83
4.80
15.13
19.17
26.08
.41
5.00
6.18
.48
46.77
5.31
22L
6.88
4.94
16.88
15.95
28.02
.36
3.10
7.28
.43
50.44
4.81
*H, 1 casing, deep
L, 4 casing, shallow
-------
WATER SAMPLES FROM ARS WELLS (SCHNEIDER), 12/17/75, GRAND JUNCTION
Well
No.
pH
EC
me/i__________________________________
Ca
Mg
Na
K
HCO 3
Cl
NO 3
SO 1 ,
pCaSO 4
2
7.71
12.86
22.34
52.04
164.13
.73
18.00
24.10
1.43
191.50
4.54
3
7.52
3.95
10.15
6.70
32.77
.25
8.10
6.26
.275
30.54
5.10
10
7.29
3.94
25.66
13.39
13.40
.48
5.36
5.68
.246
41.60
4.65
l].A
7.20
4.11
16.06
12.78
25.88
.25
920
9.84
.500
32.88
4.91
11B
7.45
5.13
23.81
15.22
31.48
.21
7.36
9.84
.464
53.04
4.65
12
7.78
21.79
20.49
49.60
405.17
.74
21.76
30.60
.784
416.47
4.51
13
7.41
4.25
23.45
14.91
18.57
.34
3.64
8.28
.296
46.69
4.65
15
7.68
17.37
22.52
127.81
241.61
.89
18.20
21.82
33.14
282.06
4.53
16
7.63
4.27
9.04
11.87
33.63
.29
16.80
9.70
.371
24.12
5.27
18H*
7.43
4.34
23.45
17.96
19.43
.39
6.60
5.54
.307
50.41
4.65
18L
7.29
6.53
15.51
20.39
58.65
1.21
11.96
7.30
3.02
70.87
4.79
19L
7.63
4.10
18.65
12.48
22.87
.26
6.50
8.00
.482
36.39
4.82
20L
7.40
4.49
16.80
12.18
26.74
.26
8.60
18.14
.877
24.99
5.00
20H
7.47
4.55
17.17
11.87
26.74
.26
9.24
18.50
.814
25.28
4.99
21
7.56
2.71
9.04
6.39
17.27
.18
5.60
4.74
.204
20.61
5.20
casing, deep
casing, shallow
*11, 1
L, 4
-------
WAI ER SAMPLES -FROM ARS WELLS (SCHNEIDER), 3/16 176, GRAND JUNCTION
Well me/l__________________________________
No. pH EC Ca Mg Na K HCO 3 Cl NO 3 SO pCaSO
1 7.46 1.22 4.25 1.87 3.92 .23 5.50 2.08 .622 3.53 6.00
2 7.47 10.31 16.88 45.43 116.90 .59 14.70 17.88 1.27 145.71 4.67
3 7.24 2.32 8.06 4.72 12.35 .21 8.10 4.80 .387 14.05 5.35
10 7.20 3.80 20.69 14.08 14.04 .40 7.20 5.22 .387 37.95 4.75
hA 7.43 4.03 12.35 13.68 25.43 .24 9.00 9.02 .789 32.88 5.01
11B 7.47 4.91 19.02 15.30 30.91 .20 8.04 9.80 .713 47.88 4.76
12 7.74 20.15 16.16 51.53 393.46 .67 20.24 28.40 1.22 402.66 4.60
13 7.50 4.61 19.50 17.75 23.32 .31 4.00 8.58 .401 48.95 4.73
15 7.48 16.56 18.55 120.48 228.98 .84 18.20 21.54 26.70 258.66 462
16 7.57 3.24 5.68 8.79 25.43 .28 15.60 7.24 .401 16.94 5.52
18L* 7.71 5.51 12.35 15.30 48.33 .92 11.80 6.32 1.03 54.33 4.92
18H 7.19 3.97 18.07 17.75 17.42 .36 5.56 4.48 .903 43.22 1.)
19L 7.63 6.43 14.02 19.38 59.29 .56 4.80 10.54 .491 76.99 4.80
19H 7.67 3.95 13.78 12.45 23.32 .25 5.90 7.64 .429 33.77 4.95
20L 7.46 4.50 13.78 12.45 27.96 .30 10.00 16.94 1.03 26.00 5.06
20H 7.65 4.35 11.87 12.05 26.69 .26 7.40 17.70 1.18 24.62 5.13
21 7.67 2.45 6.16 5.53 15.31 .17 6.00 3.84 .225 18.12 5.38
22L 7.31 4.45 15.21 18.56 25.43 .36 4.30 5.94 .276 49.76 4.82
22H 7.51 4.85 17.12 16.93 29.65 .31 3.80 6.68 .350 51.37 4.77
*H, 1 casing, deep
L, le casing, shallow
-------
TABLE A4
WATER SAMPLES FROM DRAINS, 12/17/75, GRAND JUNCTION
Drain Site No.* pH EC Ca Mg Na K HCO 3 Cl NO 3 SO pCaSOi
Lewis
1
2
3
7.62
7.64
7.75
3.93
3.99
4.54
24.74
23.08
23.45
22.22
22.22
26.48
11.25
13.83
18.57
.25
.28
.31
6.16
5.60
6.70
4.58
5.32
6.08
.265
.344
.626
45.45
44.57
51.29
4.65
4.69
4.66
Indian
1
2
3
7.75
7.72
7.72
4.04
4.25
5.08
24.00
23.45
23.08
18.56
19.78
28.91
17.27
19.86
26.74
.31
.28
.39
5.20
4.90
6.46
4.70
5.66
7.50
.727
.581
.877
46.46
47.49
62.68
4.65
4.66
4.63
Persigo
Canal
1
2
3
7.48
7.69
7.64
7.63
3.33
3.98
4.36
4.84
26.40
24.74
23.08
24.18
7.00
16.13
21.61
23.74
10.82
15.12
19.43
23.73
.21
.31
.34
.34
3.20
4.64
5.56
5.60
3.16
4.30
4.88
6.46
.228
.319
.539
.845
35.24
42.77
49.24
55.67
4.65
4.66
4.67
4.63
Hunter
1
2
3
7.64
7.79
7.70
4.34
4.18
4.25
23.08
22.34
23.81
20.69
22.22
21.00
19.86
16.84
17.27
.35
.34
.31
5.10
4.20
6.16
4.16
4.96
5.40
.447
.464
.603
52.17
57.70
45.96
4.65
4.68
4.67
Adobe
1
1.5
2
3
4
7.73
7.88
7.64
7.79
7.74
4.05
3.34
3.83
4.10
4.30
24.18
24.00
23.81
21.23
22.34
15.52
13.09
17.35
18.26
18.56
19.43
9.10
14.69
19.00
22.01
.31
.26
.31
.29
.31
5.40
3.00
5.00
4.40
7.40
4.02
3.28
4.50
5.16
6.16
.357
.675
.603
.784
.877
46.32
36.98
43.22
44.14
45.53
4.65
4.68
4.67
4.71
4.70
Little Salt
1
2
3
3.5
4
7.90
7.59
7.58
7.96
7.65
3.08
3.74
4.07
4.11
4.36
12.00
17.54
22.34
19.75
19.20
10.65
11.87
14.31
13.70
14.00
18.13
12.97
19.43
23.73
26.74
.19
.19
.28
.26
.23
6.00
556
6.00
6.80
5.80
3.20
4.44
4.54
5.08
5.64
.603
.539
.560
.519
.539
25.87
35.22
42.29
40.91
45.07
5.05
4.83
4.70
4.76
4.75
Big Salt
1 E 7.60
1W 7.54
2 E 7.70
2W 7.57
3 (main)7.52
4.16
3.34
3.83
3.71
3.52
25.29
16.06
22.71
17.54
19.38
17.35
12.48
16.74
16.13
15.52
17.27
15.55
12.54
16.84
12.97
.34
.19
.28
.22
.25
6.80
6.04
5.20
5.80
6.20
4.10
3.36
3.54
4.84
4.22
.415
.344
.500
.701
.464
47.38
30.27
43.11
34.93
33.76
4.63
4.90
4.68
4.85
4.81
I -I
I . . )
* site number increases, water moves from near Highline Canal to Colorado River.
-------
WATER SM1PLES FROM DRAINS, 3/3/76, GRAND JUNCTION
- - - -me/i
Drain Site No.* pH EC Ca Mg Na K HCO 3
-
Cl NO 3 SO 14 pCaSOt,
Lewis
1
2
3
7.64
7.65
7.71
3.85
4.18
4.79
20.06
18.94
19.06
23.36
25.21
31.17
11.74
14.83
21.67
.28
.33
.38
6.10
5.60
7.40
4.94
5.24
6.72
.230
.170
.599
43.09
48.24
57.03
4.75
4.75
4.73
Indian
1
2
2.5
3
7.66
7.08
7.39
7.68
4.04
2.59
4.96
5.09
19.19
10.83
17.81
18.19
19.24
10.61
33.02
31.17
15.48
11.41
25.91
28.04
.36
.29
.45
.43
5.10
3.00
8.60
6.60
4.20
2.88
7.56
7.56
.371
.101
.442
.599
44.91
24.29
61.58
64.00
4.75
4.08
4.74
4.72
Persigo
1
2
3
7.66
7.62
7.67
3.96
4.42
4.81
20.06
19.81
19.31
18.42
22.74
24.79
14.83
19.07
24.61
.33
.35
.38
4.76
5.64
5.50
4.42
5.82
6.94
.202
.340
.599
46.61
53.77
57.91
4.71
4.70
4.71
Hunter
2
3
7.70
7.57
4.26
4.34
19.31
19.06
23.36
22.53
17.93
19.07
.40
.36
6.44
6.04
5.88
5.52
.340
.442
50.97
49.76
4.73
4.74
Adobe
1
1.5
2
3
4
7.66
7.64
7.64
7.66
7.74
4.38
3.39
3.92
4.26
4.42
19.69
21.06
19.94
17.94
16.69
18.01
13.90
18.83
19.65
18.83
22.33
9.46
15.15
21.67
25.26
.35
.32
.25
.33
.35
5.60
4.30
5.56
5.80
6.36
4.56
3.90
5.18
6.10
6.40
.220
.549
.388
.549
.653
50.97
37.63
45.82
48.85
47.33
4.71
4.73
4.72
4.76
4.80
Little Salt
1
2
3
3.5
4
7.73
7.76
7.69
7.64
7.81
2.59
3.10
3.00
2.87
2.85
7.83
12.08
13.82
10.33
9.46
7.94
8.96
9.58
7.73
7.73
16.46
17.61
14.50
17.28
18.74
.23
.23
.24
.23
.23
5.80
4.80
5.40
5.56
5.30
3.06
3.22
3.36
3.24
2.56
.312
.251
.251
.211
.211
20.35
27.33
27.63
25.81
26.11
5.26
5.02
4.96
5.09
5.12
Big Salt
1 W
1 E
2 W
2 E
3 (main)
7.63
7.56
7.56
7.62
7.57
3.47
4.03
3.42
3.66
3.28
12.45
19.94
12.95
18.44
14.07
14.72
18.83
15.34
17.19
15.13
20.04
17.93
16.78
13.37
13.37
.23
.36
.24
.31
.28
5.76
6.20
6.40
5.90
6.10
3.18
4.86
4.70
4.46
4.00
.194
.274
.340
.326
.274
37.63
47.63
34.30
40.83
33.99
4.94
4.72
4.96
4.78
4.92
* site number
increases, water moves from near Highline Canal to Colorado River.
------- |