Water Temperature-Influences, Effects, and Control : Proceedings of the Twelfth Pacific Northwest Symposium on Water Pollution Research


WATER   TEMPERATURE
   INFLUENCES,EFFECTS, AND CONTROL
  Proceedings of the Twelfth Pacific Northwest
    Symposium on Water Pollution Research
               November 7,1963
               Corvallis, Oregon
 U.S. DEPARTMENT OF HEALTH,EDUCATION, AND WELFARE
   Public Health Service, Pacific Northwest Water Laboratory

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                    PROCEEDINGS

                      of the

        TWELFTH PACIFIC NORTHWEST SYMPOSIUM

                        on

             WATER POLLUTION RESEARCH
               WATER TEMPERATURE --
         INFLUENCES, EFFECTS,  AND CONTROL
                   Assembled by
                Edward F. Eldridge
                    Consultant
U. S. DEPARTMENT OF HEALTH, EDUCATION,  AND WELFARE

             Public Health Service

        Pacific Northwest Water Laboratory

                 Corvallis, Oregon

                 November 7,  1963

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                            AGENDA
                  TWELFTH RESEARCH SYMPOSIUM
Introduction.  Edward F. Eldridge.

Temperature as a Water Quality Parameter.  Curtiss M.  Everts.

Effects of Water Uses and Impoundments on Water Temperature.
     Robert 0. Sylvester.

Water Temperature Requirements for Maximum Productivity of Salmon.
     Roger E. Burrows.

The Effects of Temperature on Disease in Fish.  Erling J. Ordal  and
     Robert E. Pacha.

Temperature Studies on the Umpqua River, Oregon.  William H.  Delay
     and John Seaders.

Temperature Phenomena and Control in Reservoirs.  Jerome M. Raphael.

Method of Computing Average Reservoir Temperature.  Peter B.  Boyer.

Some Observations of Columbia River and Reservoir Behavior From
     Hanford Experience.  R. T. Jaske.

Instrumentation for Water-Temperature Studies.  A. M.  Moore.

Summary of Current Theories and Studies Relating to Temperature
     Prediction.  Robert Zeller.

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                         INTRODUCTION

                        E.  F.  Eldridge*
     As many of you know,  this is the twelfth  of  a  series  of  symposiums
sponsored by the Public Health Service during  the past  six years. These
symposiums have been a phase  of a Research  and Technical   Consultation
Project initiated in the Portland  office of the  Service  in  May, 1957-
They have had several  objectives:   First,  to  bring together  persons  of
this area who are  involved in research in  the Water   quality  field  in
order that each may become acquainted with the respective  interests and
research activities of  others in this field.   Second, to  investigate
the available knowledge regarding  specific  water quality   problems and
to delineate those areas where  research is  needed to  supply  new  or ad-
ditional knowledge.   And third, to stimulate  researchers  in  all  scien-
tific disciplines to conduct such research.    In  my opinion,  the  sympo-
siums have successfully accomplished these objectives.

     The initial meetings  were attended by  a  comparatively small group
(25  to  30) which was conducive to free  discussions  by  most  of those
present.   Because of the apparent interest  created by  these meetings,
attendance has  increased until approximately   150 persons were  at  the
last meeting.

     Since the Project to which I referred is  to  be incorporated  in  the
activities of the  Water Laboratory of the  Public Health Service to  be
constructed here in Corvallis,  future symposiums will  be  sponsored  by
this Laboratory.  Mr. Curtiss Everts is Director  of the Laboratory  and,
undoubtedly,  he will tell you something about the scope  and activities
planned for this facility.
     ''"Consultant, U. S. Department of Health, Education, and Welfare,
Public Health Service, Water Supply and Pollution Control Program,
Pacific Northwest, Portland, Oregon.

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           TEMPERATURE AS A WATER QUALITY PARAMETER

                      Curtiss M. Everts*
     Everyone engaged in the field of water quality control  will  quickly
recognize temperature as one of the most important measurements of the
physical characteristics of water.  In fact, the temperatures of surface
and underground waters have probably been recorded as often, if not more
so, than almost any other physical, chemical or biological  measurement
made.

     The relationships of the temperature of surface waters to the
enhancement of fish and other aquatic life, chemical and biochemical
reactions, water treatment, the toxicity of contaminants, tastes and
odors in drinking water and to the quality of domestic, industrial and
agricultural water supplies have been explored by numerous investiga-
tors.  Until recently much of the data and information obtained have
not always been put to practical  use.  Even now some areas need more
precise evaluation and study to clarify the divergent opinions ex-
pressed in some reports, to correlate the information that has been
obtained so that it may be usefully applied to the problems of water
quality control, and to check laboratory results under actual field
conditions.  It is unlikely that this will prove to be a simple task
for as we approach this point it may be expected that conflicts of
special  interest will arise that will require the judgment of Solomon
to resolve.

     In the hope that I wi11 not transgress too greatly on the remarks
to be made by the speakers that follow, I should like to offer a few
examples of the effects of temperature on water use.  You are familiar
with most of them, but it is believed that mention of them may set the
stage for some of the discussion that we hope will take place during
the remainder of this Symposium.

     Sphaerotilus, a troublesome slime in the surface waters of the
Pacific Northwest, is reported to grow extremely well in the waters of
the Columbia River at temperatures between 8 degrees and 12 degrees C.
These same temperatures are highly suitable for salmon production.  At
higher temperatures (summer 20-2U degrees C.) poor growth of Sphaerot-
il us is experienced, but these are temperatures not so suitable for
salmon.   Interestingly enough growth in the laboratory occurred quite
well throughout a range of 10 degrees to 2k degrees C.
     ""Director, Pacific Northwest Water Laboratory, U. S. Department
of Health, Education, and Welfare, Public Health Service, Division of
Water Supply and Pollution Control, Corvallis, Oregon.

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     The effects of rises in water temperatures on fish are well  known.
These include increases in metabolic rates and oxygen requirements,  in
sensitivity to toxic materials, in reduction in swimming speed,  and  in
increased avoidance reactions.

     Drinking water at a temperature of 50 degrees F. and below  is
usually considered satisfactory.  Temperatures in excess of 65 degrees
F. are likely to result in complaints,  for tastes and odors become more
noticeable as temperatures increase.  On the other hand, pathogens
survive longer at lower temperatures.

     When treatment of water is necessary for domestic consumption,
floculation and sedimentation rates increase with temperature, and the
bactericidal effects of chlorine are greater at temperatures above 20
degrees C.

     Agriculturists prefer water at temperatures above 60 degrees F.
(15 degrees C.) and this is the sort of environment that the warm-water
fishes enjoy.  Return irrigation flows usually increase temperatures in
receiving streams.

     The effects that temperatures have on dissolved oxygen concentra-
tions, on the rates of biochemical oxygen demand, and on aquatic life
are well  documented and must be reckoned with in any water quality
control program.

     Thermal stratification in water impoundments wi11 also cause
problems, particularly those with low-level turbine intakes.  This was
well illustrated in the Lower Roanoke River Basin in North Carolina
where due to stratification in the impoundments, water released at
certain times during the year was deficient in oxygen and adversely
affected downstream uses.  Use of submerged weirs to draw water of
satisfactory quality from a different level is reported to have cor-
rected this problem.

     Heat added to water which has been used for industrial and power
plant cooling purposes has an adverse effect on aquatic life, and
reduces the amount of dissolved oxygen in the water.

     Thermal pollution is rapidly becoming a problem in the Delaware
River Basin where 3-1/2 billion gallons of water daily (5*+00 cfs.)
are used for thermal electric power in the basin.  In the Chicago area
where a number of steam power plants use from 50 to 90 percent of
water available for cooling on a once-through basis, thermal pollution
is reported to be equivalent to the doubling of the organic waste load
the Illinois River now receives from the Chicago area.

     It should be obvious, therefore, that a rather concentrated effort
needs to be expended in gaining more useful knowledge on the effect of

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water use and watershed activity on water temperatures, so that reason-
able objectives can be established, and practical procedures for tem-
perature adjustment and control can be developed.  It may even be pos-
sible to use temperature variations as a means of forecasting approach-
ing changes in other water quality parameters.

     The Federal Water Pollution Control Act makes such an effort a
responsibility of the Department of Health, Education, and Welfare.
Section 2 of this act directs the Secretary to develop comprehensive
programs for eliminating or reducing the pollution of interstate waters
and tributaries thereof.  In the development of these programs it is
required that due regard be given to the improvements necessary to
conserve such water for public water supplies, propagation of fish and
aquatic life and wildlife, recreational purposes, and agricultural,
industrial  and other legitimate uses.

     This section also provides that "in the survey or planning of any
reservoir by the Corps of Engineers, Bureau of Reclamation, or other
Federal  Agency, consideration shall be given to inclusion of storage
for regulation of streamflow for the purpose of water quality control"
and that "the need for and the value of storage for this purpose shall
be determined by these agencies, with the advice of the Secretary, and
his views shall be set forth in any report or presentation to the
Congress proposing authorization or construction of any reservoir" in-
cluding storage for low-flow augmentation.

     In carrying out research, and the responsibilities for special
studies and demonstration under the act, the Secretary is directed to
develop and demonstrate "Methods and procedures for evaluating effects
on water quality and water uses of augmented streamflows to control
water pollution not susceptible to other means of abatement."

     The Public Health Service has a wealth of experience in this field
beginning with its studies in the Ohio River Basin in 1938, 1939 and
19^0 when the effects of temperature on water quality became increas-
ingly apparent.  The work of LeBosquet on the Mahoning River in the
vicinity of Youngstown, Ohio, in 19^2, where high water temperatures
from use and reuse upstream had threatened the shutdown of an impor-
tant steel  mill, resulted in Congressional approval for the release of
flood control  waters from upstream impoundments for temperature control.

     With the potential hydroelectric power development in the Pacific
Northwest far from complete, a much more complete understanding must
be obtained of the effects of impoundments on downstream temperatures
so that  suitable preventive or protective measures may be developed
for existing storage and incorporated into any new impoundments pro-
posed for the future.

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     With these facts in mind, the Pacific Northwest Water Laboratory,
scheduled for construction under Section k of the Federal Water Pollu-
tion Control Act, will have, among its chief objectives, a precise
study of the effects of multiple-purpose impoundments on downstream
water use.  We would also expect to carefully investigate the effects
of watershed use on water quality.  In both of these areas temperature
will be a most important area of concern.

     This work will not be exactly new to Oregon and the Pacific North-
west for it has already been recognized that at least one of the impor-
tant contributions that can be made by low-flow augmentation will be
that of temperature control.  Such a program is included for the im-
poundments  in the Rogue River Basin, and is now under study in the
Umpqua River Basin.

     Over ten years ago the Pollution Control Council, Pacific North-
west Area,  included the control of high temperature wastes as part of
its water quality objectives.  Similar criteria may be found in the
regulations of other water quality control agencies.

     Construction of the laboratory is expected to begin in February,
196^ with completion scheduled for the summer of 1965-   In the meantime,
the task of assembling a competent staff of engineers, scientists, and
supporting  personnel will proceed as rapidly as appropriations for this
purpose will permit.  When the staff becomes operational, it will be
engaged in  a program of research technical assistance on water quality
problems in an area which includes Idaho, Montana, Oregon, Utah,
Washington, and Wyoming.  Training will also be an important function
of the laboratory staff.

     As one of the arms of the Public Health Service, we would expect
to furnish  substantial support for any of our activities in the field
of water quality control, and would hope that through our efforts and
with your help some of the answers on temperature-water  use relation-
ships wil1  be found.

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   EFFECTS OF WATER USES AND IMPOUNDMENTS ON WATER TEMPERATURE

                      Robert 0. Sylvester*


                          Introduction

     The natural temperature rise or fall  of a water body is established
by a number of meteorological and physical factors.  Meteorological  fac-
tors influencing water temperature are the amount of solar radiation,
wind velocity, air temperature and vapor pressure.  Physical  factors are
the surface area exposed, water depth, water temperature, rate of water
exchange, mixing afforded, shading from vegetation or land masses,
impurities in the water, surface and subsurface inflows, and the temper-
ature of the surrounding land mass.  The most important factor is the
amount of solar radiation absorbed, which for a given mass of water  is
a function of the exposed water surface area.

     The amount of solar radiation striking a given body of water de-
pends upon the season of the year, geographical location, time of day,
elevation, shading, amount of particulate matter and water vapor in  the
atmosphere,  and quantity of indirect solar radiation.  On striking a
water surface, a portion of the light is reflected, perhaps 5 to 35  per-
cent, depending upon the angle of incidence (1).  Light penetrating  the
water is absorbed at different depths depending upon the wave length of
the light and the amount of suspended and dissolved substances in the
water which limit the amount of penetration.  The longer wave lengths
(red and orange) and the shorter rays (ultra-violet and violet) are
reduced more quickly than the middle-range wave lengths of blue, green
and yellow.   The first meter of depth may absorb or extinguish 53 per-
cent (1) of the total incident light where it is transformed into heat.

     Water temperature is influenced by land temperature, especially in
the case of irrigated areas with their return flows.  The specific heat
of water is high compared with other materials and it thus becomes a
stabilizer of temperature and an important factor in soil temperature.
Evaporation from wet soil surfaces together with the relatively high
specific heat of the wet soil, will cause it to have a temperature much
lower than that of a- dry soil under the same conditions.  The original
source of energy for evaporation is solar radiation which can be di-
vided into three parts:   direct solar radiation; heat that reaches the
evaporating  surface from the air; and heat that is stored in the evap-
orating body.  Part of the incoming solar radiation is reflected from
the surface back to the sky and may amount to 25 percent (k) for a sur-
face covered with vegetation. ' Perhaps 10 to 15 percent of the incoming
     '"'Professor of Sanitary Engineering, University of Washington,
Seattle.

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radiation is radiated back to the sky, depending upon the temperature
of the earth's surface and of the atmosphere above.  The remainder of
the solar radiation is used in evaporation and in heating the soil and
the air in contact with the soil.  When the soil is very moist, more
than 80 percent (k) of the net radiation is used in evaporation.  When
the soil is dry, most of the radiation is used in heating the air.

                         Heat Budgets

     Included in the heat budget for a body of water would be the heat
gain from solar radiation, the heat loss by evaporation, the heat gain
or loss by conduction, the heat loss by radiation, and the heat con-
tained in the inflow and outflow of the system.  With time and a uniform
meteorologic condition, a body of water would tend to come into equilib-
rium wherein the heat losses would balance the heat gains.  This condi-
tion is approached in large shallow reservoirs and in long streams where
the diurnal temperature changes become uniform and of about equal mag-
nitude.

     The amount of heat that a body of water will absorb or release can
be expressed as follows:

        H = f(A,M,V)

where   H - heat loss or gain

        A = surface area

        M = mixing afforded by advection, wind or channel configuration

        V = volume of water involved

     The rate of heat release or absorbence can be expressed as:

        Hr = f Tw, W, Vp)

where   Hr = rate of heat gain or loss

        Ta = air temperature

        Tw = water temperature

        W  = wind velocity

        Vp = vapor pressure of the atmosphere

     Velz (2) presents the following equation for computing heat  loss in
a body of water.  Heat gain can be computed from the same equation by re-
versing the sign of the air and water temperature; by making solar radia-
tion and conduction a gain; and by subtracting evaporation and radiation,

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     H = To.00722 HVC (1 + 0.1W) (Vw - Va)~| + |~(0.8 + 0.16W)  (Tw  -  Ta)~]

            + p.O (Tw - Ta)l -  Hs


     where the first term is heat loss by evaporation,  the second is
     heat loss by conduction, the third is heat loss by radiation and
     the fourth is heat gain by solar radiation.

        H  = heat loss in Btu per hour per sq. ft.  of water surface

        Hv = latent heat of vaporization for a given water temperature

        C  = a constant ranging from 10 to 15> depending upon the
             depth and exposure of the water body

        W  = mean wind velocity in miles per hour

        Vw = vapor pressure of water in inches of H_ near water surface

        Va = mean absolute vapor pressure in the overlying atmosphere

        Tw = water temperature at the surface, °F.

        Tg = mean air temperature, °F.

        Hs = Btu per hour per sq. ft. of solar radiation

                    Temperature Comparisons

     There is a dearth of reported temperature data on Northwest  streams
obtained prior to man-produced changes in the stream heat budget.  Com-
parison of water temperatures before and after an act of man are subject
to question unless all the variables can be held constant in the two
periods or can be accounted for by calculation.  In a natural stream
flowing from an upland to a lowland environment, there will be a normal
natural temperature increase or decrease that must be known before arti-
ficial  causes of temperature change can be evaluated.  In the ^2-mile
stretch of the Wenatchee River between Lake Wenatchee and Dryden, man's
activity has produced little effect on the river's natural temperature.
Thermograph records (5) of the Chelan County P.U.D. show average monthly
natural temperature changes (Table 1) as the river flowed from the up-
land to the lowland environment.  These temperature changes might be
considered typical of a moderate-sized stream in the Northwest as most
of our streams have storage on the headwaters, although they are not
all surface drawoff as in Lake Wenatchee.  Raphael  (11) (12) has calcu-
lated that under natural conditions in August, the Columbia River tem-
perature will rise about 1°F. in a 72-mile stretch below Chief Joseph
Dam and about 1°F. in a 50-mile stretch below Rock Island.
                               8

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    Table 1 - Natural Temperature Changes in the Wenatchee River,
            Lake Wenatchee to Below Dryden, 1956 (5), °F.
                       Feb.   Apr i1   June   Aug.   Oct.-   Dec.
    Lake Wenatchee     34.0    38.1   44.6   57.6    51.6   37-9
    Below Oryden       32.8    42.0   46.7   61.4    47.7   36.4
    Difference         -1.2    +3.9   +2.1   +3~7S    -3.9   -1.5
      *Year  1955

     In a computer analysis of Lower Columbia River water quality (8),
correlation analyses were made between the various quality constituents.
Table 2 shows these correlations with water temperature for the entire
year of I960, using the power function equation since it gave the best
correlations.  If one considers a correlation of 0.55 or above to be sig-
nificant, then the only significant correlations with temperature, other
than dissolved oxygen, on a yearly basis are those involving activity of
the biota, such as phosphate, nitrite and nitrate, and chlorophyll.  Flow
rate very definitely affects water temperature as examined on a month-by-
month basis but not on a yearly basis, since low flows occur under both
warm and cold climatic conditions as may the higher flows.  Feigner (15)»
in an evaluation of temperature control by low-flow augmentation, con-
cludes that flow requirements increase exponentially with temperature
rise.

    Table 2 - Correlation of Water Temperature with Water Quality,
                     Lower Columbia River, 196oi/

            Flow                                    0.22
            pH                                      0.54
            Dissolved Oxygen                        0.81
            Total  Solids                            0.32
            Suspended Solids                        0.18
            Biochemical  Oxygen Demand               0.14
            Alkalinity                              0.22
            Hardness                                0.24
            Most Probable No. Coliforms             0.29
            Sulfate                                 0.13
            Phosphate                               0.61
            Ammonia                                 0.40
            Nitrite                                 0.62
            Nitrate                                 0.76
            Total  Nitrogen                          0.55
            Pearl  Benson Index                      0.37
            Chlorophyll  a                           0.83

    \J From reference (8), using power function equation Y = A + B(X)
       + C(X)2.  Highest correlation shown with temperature as the
       independent or dependent variable.  Correlations above 0.55
       are considered significant.

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     Figure 1 shows downstream temperature changes in August on four
different rivers east of the Cascades which are representative only
for the years indicated.  The Columbia River in the 450 miles between
Grand Coulee Dam and Bonneville rose 5.4°F., the sharpest rise occur-
ring between Pasco. and Umatilla due to the warm inflow of the Snake
River.  In the warm year of 1958, while the Brownlee and Oxbow Reser-
voirs were first being filled on the Snake River, the mean August water
temperature rose to 74°F. at Clarkston.  In the more moderate year of
1959, after the dams were in operation, a temperature drop of about 3°F.
was observed below the Brownlee Reservoir, rising another 2°F. through
the Oxbow Reservoir and then falling off to 69°F. at Clarkston.  The
Yakima River receives most of its irrigation return flow in the 80-mile
stretch between Parker and Kiona where the large majority of the flow
in August consists of irrigation return water.  Figure 1 shows a tem-
perature rise in this stretch of 12=2°F. to a monthly average of 73-20F.
at Kiona whereas in the preceding stretch of 90 miles, the river tem-
perature rose only 2.7°F.  The Wenatchee River in flowing some 40 miles
from Lake Wenatchee to Dryden exhibits a gradual  temperature rise of
1.5°F. as there is little effect herein by man's activities.  This com-
pares closely with the temperature rise in the Upper Yakima River.  It
should be pointed out that these temperature changes vary, depending
upon the year in which the comparisons are made.

             Effect on Stream Temperature by Usage

     Data are sparse in showing specific changes in river water temper-
atures from various water uses.  Thermal power plants and return of
cooling water from various industries are perhaps the chief source of
temperature pollution.  Hoak (9) reports that the installed capacity of
thermal  power plants is doubling about every decade.  Monongehela River
temperatures have risen to 98°F. because of industrial water return,
and then cooled to 87°F. in a distance of 1.4 miles.  He states that
because of the concentration of industry, the heat raised at one point
is not always dissipated before another temperature rise occurs.  In a
study of Columbia River water temperatures between Priest Rapids and
Umatilla, Rostenbach (13) concludes that natural  climatic and river
conditions caused a greater temperature variation in the Columbia River
for the 19^4-55 period than did the effluents from the Hanford reactors.
Oil refinery effluent temperatures observed in the period of 1959-61
in northwest Washington ranged from 72.5 to 83.5°F.

     Water,  in passing through a municipal water system and subsequently
through a sewerage system, experiences a rise in temperature that may or
may not be significant, depending upon the size of the receiving water.
Table 3 presents temperature data in the Tacoma and the Seattle (Alki)
sewage treatment plant effluents.  Both plants are of the "primary"
treatment type.   Although the years of comparison are different, both
plants have a similarity in effluent temperatures.  Tacoma's water sup-
ply is obtained largely from the Green River and Seattle's from the
                              10

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COLUMBIA RIVER BASIN WATER TBMPBRATURES IN AUGUST
Downs tream
66
64
62
Q>
Columbia River. 19SS (ref. 3)
o
•a
a
Snake River; 1958. 1959 (ref. 6)
74
72
70
68
H)
M

U
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adjacent Cedar River. The data in Table 3 for Puget Sound area condi-
tions indicate that the treatment plant effluents are warmer than the
diverted water by about 14°F. in the winter, 12°F. in the spring, 9°F.
in the summer, and 13°F. in the autumn. Additional data are needed on
water temperature increase through municipal use.
Year
Table 3 - Sewage Treatment Plant Effluent Vs.
River Temperatures, °F.

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Green River Intake
1961 I/
1962 2/
1963 2/
k]
kk
36
ko
39
37
41
39
41
^3
43
43
44
44
48
48
50
54
55
57
57
59
58
59
50
58
60
46
49
55
41
43
--
42
39
--
1961
1962
1963
1960
I960
Tacoma Sewage Treatment Plant
54
55
57
54
56
57
57
54
58
59
59
57
62
59
60
64
61
68
64
63
67
67
64
67
65
64
65
62
62
61
61
62
--
54
57
--
Cedar River Intake

39.5 40.1 40.6 44.6 48.5 52.8 56.4 54.0 51.1 48.8 43-3 40.3

Seattle Alki Sewage Treatment Plant 1'

53 53 52 55 58 60 63 64 62 61 55 55

\J Prior to Howard A. Hanson Dam Impoundment.
Temp, taken dai1y.
2/ After Howard A. Hanson Dam Impoundment (during period of
May to October) thermograph records.
3/ Daily thermometer reading.
Irrigation Return Flow:

The use of river water for irrigation may have beneficial as well
as detrimental effects in regard to water temperature. Water is normally
stored to increase the irrigation season base flow of the river above
the points of diversion. If this water is stored in fairly deep reser-
voirs at higher altitudes, it will result in water temperatures above
the points of diversion being lower than would prevail under summertime
conditions of natural flow. However, downstream from points of diver-
sion where water is diverted so as to decrease the streamflow below its
12
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1.35 AC-FT/AC OF
SUBSURFACE SEEPAGE,
APRIL-SEPTEMBER
SALTS, 615 LBS AC
1.35 AC-FT/AC
1230 LBS/AC
SALTS APPLIED
TO SOIL
1.3 AC-FT/AC
WASTAGE,
APRC-SEPTEMBER
SALTS, 300 LBS/AC
SALTS
TO GROUND WATER STORAGE
FOR RELEASE, OCTOBER-MARCH.
SALTS, 615 LBS/AC
2.7 AC-FT/AC
SOIL COLUMN PERCOLATION,
APRIL-SEPTEMBER
2.6 AC-FT/AC
EVAPO-TRANSPIRATION
LOSS,
APRIL-SEPTEMBER
1530 LBS/AC
FROM RIVER
1 M 1 _LL
6.6 AC-^T/AC
DIVERTED FROM
YAKIMA RIVER,
APRIL-SEPTEMBER
''fz.
Fig. 2
FATE OF DIVERTED IRRIGATION WATER
AND ITS SALTS, YAKIMA RIVER BASIN, 1959-60
13
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normal rate, water temperatures would be raised above those otherwise
occurring. The return of spent irrigation waters may raise or lower
the receiving stream temperature, depending upon the method of conduc-
ting this return flow.

Figure 2 will serve to illustrate the fate of water diverted for
irrigation in the Yakima River Basin which can be considered typical of
an irrigated area. Of 6.6 acre-feet per acre of diverted water in the
April-September irrigation season (10), 1.3 acre-feet per acre is wast-
age resulting from over-irrigation and from canal spillage. This water
returns to the parent river in open drains during which time its tem-
perature is increased. Of the remaining 5-3 acre-feet, 2.6 acre-feet
(about 50 percent) is lost to evapotranspiration. This large evapo-
transpiration loss is responsible for the soil-cool ing effect discussed
previously. About 2.7 acre-feet per acre of the previously diverted
water passes through the soil column into the groundwater stratum where
about half of it returns to the parent stream during the irrigation
season and the other half returns from bank storage during the non-
irrigation season. (The groundwater table rises during the irrigation
season and falls during the non-irrigation season.) This groundwater
seeps into open drainage channels or is conveyed to open channels via
subsurface drains. The great majority of the soil drainage in the
Yakima Valley is comprised of open drains.

Table 4 illustrates some of the water temperature changes observed
in the Yakima Valley irrigation facilities during August of 1959 and
I960. On the average, water temperature increases of 3«5°F. are expe-
rienced in 37 miles of main canal flow.

Table k - Irrigation Water Temperature, Yakima Valley,
August 1959-1960 -- Mean Values in °F. (10).