WATER POLLUTION CONTROL RESEARCH SERIES • 13030 DYY 6/69
WATER QUALITY MANAGEMENT PROBLEMS
IN ARID REGIONS
U.S. DEPARTMENT OF THE INTERIOR • FEDERAL WATER QUALITY ADMINISTRATION
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe
the results and progress in the control and abatement
of pollution of our Nation's waters. They provide a
central source of information on the research, develop-
ments and demonstration activities of the Federal Water
Quality Administration,, Department of the Interior,
through inhouse research and grants and contracts with
Federal, State, and local agencies, research institutions,
and industrial organizations.
Water Pollution Control Research Reports will be
distributed to requesters as supplies permit„ Requests
should be sent to the Planning and Resources Office,
Office of Research and Development, Federal Water
Quality Administration, Department of the Interior,
Washington, D. C. 20242.
Additional copies of this report may be obtained by
addressing a request to:
Treatment and Control Research Program
Robert S Kerr Water Research Center
P 0 Box 1198
Ada, Oklahoma 74820
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WATER QUALITY MANAGEMENT PROBLEMS
IN ARID REGIONS
Edited by
James P. Law, Jr.
Research Soil Scientist
and
Jack L. Witherow
Chief, Agricultural Wastes Section
Treatment and Control Research Program
Robert S. Kerr Water Research Center
Ada, Oklahoma 74820
for the
FEDERAL WATER QUALITY ADMINISTRATION
DEPARTMENT OF THE INTERIOR
Program //13030 DYY
October, 1970
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FWQA Review Notice
This report has been reviewed by the Federal
Water Quality Administration and approved for
publication. Approval does not signify that
the contents necessarily reflect the views
and policies of the Federal Water Quality
Administration, nor does mention of trade
names or commercial products constitute
endorsement or recommendation for use.
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FOREWORD
An international conference entitled "Arid Lands in a Changing World",
sponsored by the American Association for the Advancement of Science
Committee on Arid Lands and the University of Arizona, was held at
Tucson in June, 1969.
The Federal Water Quality Administration provided financial support for
the conference and solicited papers to be presented in the Water Manage-
ment and Salinity and Desalinization sessions. This report presents a
selected group of the papers presented at those sessions which will benefit
those concerned with water quality management problems in arid regions.
The editors wish to acknowledge the cooperation they received from the
authors in the completion of this task.
James P. Law, Jr.
Jack L. Witherow
Ada, Oklahoma
October, 1970
iii
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CONTENTS
PAGE
NITRATE REMOVAL FROM AGRICULTURAL WASTEWATER J"~
Percy P. St. Amant and Louis A. Beck
THE EFFECTS OF SALINITY STANDARDS ON IRRIGATED AGRICULTURE 9
IN THE COLORADO RIVER BASIN
Gary N. Dietrich and L. Russell Freeman
PROBLEMS OF POLLUTION OF IRRIGATION WATERS IN ARID REGIONS 17
H. B. Peterson, A. A. Bishop, and J. P. Law, Jr.
WATER QUALITY REQUIREMENTS AND RE-USE OF WASTEWATER EFFLUENTS 37
Stanley J. Dea
SALINITY CONTROL IN RETURN FLOW FROM IRRIGATED AREAS - 45
A DEMONSTRATION PROJECT
Norman A. Evans
WATER QUALITY CONTROL PROBLEMS IN INLAND SINKS 57
Richard C. Bain, Jr. and John T. Marlar
NATURAL POLLUTION IN ARID LAND WATERS 79
John M. Neuhold
DISTILLATION OF WASTEWATERS: A WATER RESOURCE FOR ARID REGIONS 85
Allen Cywin, George Rey, Stanley Dea, and Harold Bernard
ANIMAL WASTE RUNOFF - A MAJOR WATER QUALITY CHALLENGE 95
Anthony V. Resnik and John M. Rademacher
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NITRATE REMOVAL FROM AGRICULTURAL WASTEWATER
by
Percy P. St. Amant and Louis A. Beck —
The San Joaquin Valley of California is the largest single agricultural
area in the State. The nearly eight million acres (3.24 x 10" ha) of
irrigable land of this Valley is one of the richest agricultural areas
in the world. Massive water import facilities have recently been
constructed to assure that sufficient water is available for irrigation.
Now that water is available much of the irrigable land is being developed
for crop production. However, as often happens, the solving of one
problem develops another. This problem is how to dispose of the saline
agricultural wastewaters that result from irrigated agriculture. The
U. S. Bureau of Reclamation has begun construction of the San Luis
Drain to transport these wastewaters from Kettleman City on the south
to the western edge of the Sacramento-San Joaquin Delta near Antioch.
The State is continuing studies with the aim of constructing a drain
at a later date to provide drainage for the rest of the Valley.
In 1965, the Federal Water Pollution Control Administration (FWPCA)
began an investigation of the effects of the proposed San Joaquin Master
Drain upon the quality of receiving waters. (The San Joaquin Master
Drain considered both the Federal and State drainage facilities.)
In 1967, the FWPCA report "San Joaquin Master Drain Effects on Water
Quality of San Francisco Bay and Delta" indicated that serious pollution
problems would likely result if the wastewaters were discharged into
the Bay System. Nitrogen, primarily in the nitrate form, is the most
serious potential pollutant. This report also recommended that no
wastewater be emptied into the Bay System until a suitable method for
nitrate removal has been developed and that studies be vigorously
pursued during 1967, 1968, and 1969 to firmly establish the economic
feasibility of nitrogen removal treatment of San Joaquin Valley agricultural
wastewaters.
In January 1967, representatives of the U. S. Bureau of Reclamation
(USSR), the FWPCA, and the California Department of Water Resources (DWR),
met to discuss the findings of the FWPCA's report. It was at this time
that the Interagency Agricultural Waste Water Treatment Center was
established. The objective of the Center was to determine an economically
feasible method of removing nitrogen from the agricultural wastewaters
of the San Joaquin Valley. The estimated Summer peak wastewater flow
into the Bay System after the year 2000 will be about 700 million gallons
per day (2.65 x 10 cu m/day). The estimated constituent concentrations
in San Joaquin Valley agricultural wastewaters is shown in Table 1.
— Project Director, San Joaquin Project, Federal Water Pollution
Control Administration; and Chief, Quality and Treatment Unit, California
Dept. of Water Resources, Fresno.
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TABLE 1
ESTIMATED CONSTITUENT CONCENTRATIONS IN
SAN JOAQUIN VALLEY AGRICULTURAL WASTEWATERS
Chemical Constituents
Concentrations in mg/1
Minerals
Initial
After 50 yrs of Operation
Calcium
Magnesium
Sodium
Potassium
Carbonate
Bicarbonate
Sulfate
Chloride
Nitrate
Boron
Total Dissolved Solids
220
160
1,900
20
0
220
3,500
1,000
90
11
6,800
160
90
540
10
0
200
740
670
90
3
2,500
Non-Time Varying Constituents
Concentrations in mg/1
Nutrients
Total Nitrogen
Total + Organic Phosphate
Pesticides
Others
Dissolved Oxygen
5 Day B.O.D.
C.O.D.
Sufactant (ABS)
Phenolic Material
Grease and Oil
21
0.35
<0.001
5-10
1-3
10-20
0.0
0.001
0.5
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Prior to 1967, the California Department of Water Resources had made
arrangements to utilize U. S. Bureau of Reclamation land along the
Delta-Mendota Canal near Firebaugh, California, for construction of
pilot-scale algae stripping facilities. With the start of the
Interagency study, this area was expanded to include space for
desalination and bacterial denitrification studies. The organization at
the Firebaugh Treatment Center is quite unique (Figure 1). The most
unique feature of the Center is the intermingling of personnel. The
Center is guided by a committee consisting of a project director from the
DWR and the FWPCA and a designated representative from the USER. This
committee is assisted by a Board of Consultants comprised of Drs. Oswald,
Golueke, and McCarty. Essentially, the work at the Center is providing
each of the three agencies with more information at a lesser cost than
would have been possible with three separate single-agency studies.
Methods of nitrate removal being studied at the Center include algae
stripping and bacterial denitrification. Two methods of bacterial
denitrification are being evaluated: pond denitrification and filter
denitrification. Desalination is also being evaluated.
Desalination
The FWPCA, through an agreement with the Office of Saline Water (OSW),
is evaluating two methods of desalination of agricultural wastewaters—
reverse osmosis and electrodialysis. The reverse osmosis unit evaluated
was operated at a pressure of 750 psi (52.7 kg/sq cm) using a cellulose
acetate membrane. With this unit up to 93 percent ion removal was
experienced using 6,000 mg/1 wastewater. In the electrodialysis unit
tested, about 30 percent of the ions were removed each time the waste-
water was passed through the membrane stack. Of the two units evaluated,
neither unit significantly removed the boron ion. The reverse osmosis
unit removed about 20 percent of the nitrate ions, while the electro-
dialysis unit removed about the same percentage as it did the other ions.
Algae Stripping
The basic theory of algae stripping to remove nitrogen is quite simple--
grow a crop of algae which ties up the nitrogen in their cell structure
and then remove the algae from the water. However, it is not as simple
as it sounds. While algae will grow quite easily in this water, the
dense crop of algae required to remove 90 percent of the nitrate-nitrogen
is another problem. Our studies at Firebaugh have indicated that the
agricultural wastewaters lack both phosphate and iron in the amounts
required to grow this dense crop of algae. We have tied up 90 percent
of the nitrogen in the algal cell structure with the addition of phosphate
and iron. Algal nutrition studies were conducted in flasks at the Center.
The effect of individual growth parameters (nutrients, depth, detention
time, mixing, etc.) were studied in small growth units. The results of
the experiments in the small growth units were combined to determine the
operating conditions for the quarter acre growth pond. The results from
this large growth pond were then scaled up to prototype size.
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FIGURE I - ORGANIZATION CHART
AGRICULTURAL WASTE WATER TREATMENT CENTER
FIREBAUGH
TECHNICAL COORDINATING COMMITTEE
COO/fO/NATOK
(t/SBK)
C6QK0/NATO*
fft*PC A)
DATA
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The removal of the algae from the water is an even more difficult
problem than growing a dense crop of algae. Methods which will be
investigated at Firebaugh for algae removal include centrifuging and
micro-screening. The most promising method, however, is flocculation
and either sedimentation or flotation. We have been able to achieve
over 95 percent removal of algal cells by flocculation and sedimentation
using either alum, lime or polyelectrolytes--all at approximately the
same cost. After we have concentrated the algae by either sedimentation
or flotation, it must be dewatered. This summer we will be operating
pilot-scale units to test dewatering by centrifugation and vacuum
filtration.
The disposal of the algae may pay part of the cost of treatment.
Several concerns have expressed interest in the use of algae for such
things as animal feed, soil conditioner, or for production of adhesives.
In livestock feed, algae would replace the fish meal or protein supplement
and have a value of approximately $150 a ton ($165/metric ton).
Poultry raisers are also interested in using algae for feed. Besides
the protein, algae contains xanthopyll, which adds color to the flesh
of the bird and to the egg yoke and increases the market value. The
company interested in using algae as a soil conditioner predicts that
algae may be used by the home gardener similar to the use of Milorganite
(condition the soil as well as having some fertilizer value.) Algae
would have a value of about $100 a ton ($110/metric ton) as a soil
conditioner. A value of about $120 a ton ($132/metric ton) could be
realized by utilizing algae in the production of adhesives. If none
of these methods of disposal are practiced, it may be necessary to
dispose of algae by digestion. The methane gas produced could be used
to provide power required for the treatment process. Laboratory
experiments by Dr. Oswald indicate that the methane produced by digestion
would produce more power than required in the treatment process.
Bacterial Denitrification
Bacterial denitrification is accomplished through the use of micro-
organisms which, in the absence of dissolved oxygen, oxidize organic
material and reduce the nitrate-nitrogen to nitrogen gas. A wide
variety of common facultative bacteria have the ability to bring about
denitrification. Denitrification of nitrates is a two-step process
in which the nitrates are reduced to nitrites and then to nitrogen gas.
This method poses no by-product waste disposal problem. However, the
organisms can only achieve denitrification if they are supplied with
an organic energy source. Since the agricultural wastewaters are very
low in organic materials, it is necessary to add an organic source to
the water. At the Firebaugh Treatment Center methanol is added to the
wastewater to supply this required organic source. We are actively
evaluating two methods of bacterial denitrification at the Firebaugh
Center: pond denitrification and filter denitrification.
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Pond Denitrification
Relatively deep ponds are used in this process to develop the required
anaerobic conditions. After methanol addition, the wastewater enters
near the bottom of the pond at a detention time of 5-20 days and the
nitrogen-free water is discharged at the top of the pond. The denitrifying
organisms are free-floating in the pond with the more dense concentration
near the bottom.
This denitrification method was initially proposed by Dr. Perry L. McCarty.
In order to determine if this process would work under field conditions,
3-ft. (0.91 tn) diameter pipes, 6 to 11 feet deep (1.83 m to 3.35 m) were
installed to simulate deep ponds. The simulated ponds demonstrated that
this process of denitrification would work under field conditions. Based
on these results, two deep ponds were constructed at the Center. One pond
is 60 feet (18.3 m) by 200 feet (61.0 m); the other 50 feet square (15.2 m).
Both ponds are approximately 14 feet deep (4.28 m). The larger pond is
covered with a floating styrofoam material to reduce algal growth and
surface reaeration.
In August 1968, pilot-scale studies began using these two ponds. A
nitrate-nitrogen removal of 90 percent has been achieved in the larger pond
at a ten day detention time. The smaller pond has experienced hydraulic
short-circuiting, thus reducing the nitrogen removal efficiency. These
problems have now been corrected and the pond is now operating. Preliminary
data this winter indicate that an increase in the detention time may be
necessary as the water temperature drops.
Filter Denitrification
This method is very similar to the deep pond process except an aggregate
bed is used. An advantage of this method over the pond system is that the
surface area to which the organisms can attach themselves is greatly
increased, thus producing a greater concentration of bacteria. Also since
the bacteria have something to which they can attach themselves, the waste-
water can be passed by the bacteria at a higher velocity without washing
them out as would happen in a deep pond where the bacteria are "free-floating."
Because of these advantages, the nitrate-nitrogen is reduced to nitrogen
gas more quickly than in deep ponds.
All filter denitrification studies at the Firebaugh Center have been
performed in upflow columns with a 6-ft. (1.83 m) media depth. Methanol
is added to the wastewater just before it enters the bottom of the filter.
Initial filter studies were accomplished using 4-inch (10.2 cm) diameter
pipes. These small pipes demonstrated that this process would work well
under field conditions. Based on these results 18-inch (45.7 cm) and 36-inch
(91.4 cm) diameter filters were installed.
The major variables investigated have been detention time and filter
media. Some of the various media evaluated include sand, activated carbon,
gravel, volcanic cinders, coal and a commercially produced trickling filter
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media. The most satisfactory media has been one-inch (2.54 cm) diameter
gravel. Smaller diameter media were investigated but after several
months of operation the head loss through the filters was greater than
experienced in the one-inch (2.54 cm) diameter media. The majority
of the head loss through the filter is caused by the dense bacterial
mass within the filter. As the bacterial mass builds up and the head
loss increases, short-circuiting will begin to occur within the filter
thus reducing the nitrogen removal efficiency. Some of the filters
have been operating continuously for nearly a year without requiring
cleaning due to bacterial build-up. The head loss through these filters
has not significantly increased during this continuous period of
operation.
The detention times evaluated have been two hours, one hour, and one-
half hour. All filters have a minimum of quarter point sample ports
so nitrogen removal profiles can be studied. At all detention times
studied greater than 90 percent removal of the 20 milligrams per liter
(mg/1) of nitrate-nitrogen has been achieved. However, during periods
when the influent wastewater is below 10°C, the removal efficiency
of the filters is reduced. Studies are presently underway to try to
better define the temperature effect on the bacterial denitrification
system. From data collected thus far, it appears that a filter using
one-inch (2.54 cm) diameter aggregate at a one-hour detention time will
be effective in removing 90 percent of the 20 mg/1 of influent nitrate-
nitrogen at temperatures above 12°C.
A larger filter, 10 feet (3.0 m) square, has recently been constructed
at the Center. This filter, filled with one-inch (2.54 cm) diameter
aggregate, will be used to evaluate hydraulic characteristics of large
upflow filters.
Comparison of Biological Denitrification Methods
As mentioned earlier, estimated flows from the San Joaquin Valley will
approach 700 million gallons per day (2.65 x 10 cu m/day) after the
year 2000.
The land requirements for the three denitrification methods will vary
greatly, based on present knowledge. The algae stripping method will
require about 9,000 acres (3645 ha) of land, pond denitrification
about 1,100 acres (445 ha) and filter denitrification about 150 acres
(60.8 ha).
At 700 mgd (2.65 x 106 cu m/day) the algae stripping method will produce
approximately 450 tons (410 metric tons) per day of dried algae. The
bacterial denitrification systems produce no usable by-product.
Initial estimates project the costs of these three biological systems
nearly the same—around $10 per acre foot ($8.10/1000 cu m), or $25
to $30 per million gallons ($6.60 to $7.90 per million 1). Recent
reduction in the cost of methanol may further reduce the cost of
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bacterial denitrification. Also the original cost for the algae
stripping method did not include any return for the dried algae which
may also reduce the cost of this system.
The California Department of Water Resources cost estimates for the
formerly planned Master Drain are about $110 million for Western Delta
Area discharge, and about $250 million for direct ocean disposal.
At a treatment cost of $10 per acre foot ($8.10/1000 cu m) the capitalized
cost of conveyance, treatment, and discharge into the Western Delta
is about two-thirds the cost of direct ocean disposal.
Our objective at the Interagency Agricultural Waste Water Treatment
Center is to develop an economically feasible method of removing the
nitrogen from the agricultural wastewaters of the Valley. In order
that construction of the wastewater disposal drain can continue as
scheduled, we must have the answer by January 1970. We are actively
refining the nitrogen removal systems so accurate economic evaluation
can be made by that date.
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THE EFFECTS OF SALINITY STANDARDS
ON IRRIGATED AGRICULTURE IN THE
COLORADO RIVER BASIN
by
Gary N. Dietrich and L. Russell Freeman —
The Federal Water Pollution Control Act, as amended, authorizes the
establishment of water quality standards for interstate waters. These
standards are to provide for the preservation and enhancement of water
quality and the protection of present and potential water uses. The
Act gives the States the opportunity to develop and adopt the standards
and submit them to the Secretary of the Interior for his approval and
adoption as Federal standards. Where he finds the State standards
unacceptable, the Secretary is empowered to promulgate Federal standards.
State enforcement of standards is encouraged; however, Federal enforce-
ment is possible. All but one of the States, the District of Columbia,
Puerto Rico, the Virgin Islands and Guam have adopted standards, and
these have been fully or partially approved as Federal standards.
This paper discusses salinity criteria for the Colorado River Basin.
Although salinity criteria ordinarily would be included in the water
quality standards, the seven States of the Colorado River Basin concluded,
after careful consideration, that sufficient information was not available
to develop and implement such criteria. The Secretary of the Interior
concurred in this decision and further determined that studies should
be undertaken to develop the basis for formulating equitable, workable
and enforceable salinity criteria. Consequently, the water quality
standards adopted and approved for the Colorado River and the other
interstate waters of the Basin are void of mineral quality criteria,
or salinity criteria as they are commonly called. The task of
formulating such criteria has been deferred pending the development of
the capacity and knowledge to perform this task.
Salinity criteria present some significant and even serious implications
for irrigated agriculture, hence the reason for selecting this topic
for discussion. It is to be noted that other aspects of water quality
standards -- sediment and turbidity criteria and nutrient, pesticide
and even temperature criteria -- also apply to and affect irrigated
agriculture. However, to enable an adequate treatment of the salinity
criteria issue, a discussion of these other aspects is not included
in this paper.
Salinity is the most serious water quality problem in the Colorado River
Basin. Like many streams in the arid West, the Colorado River displays
a progressive increase in salinity between its headwaters and mouth.
—' Respectively, at the time of presentation, Deputy Director,
Division of Technical Support and Deputy Director, Colorado River-
Bonneville Basins Office, Federal Water Pollution Control Administration.
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Currently, the average salinity concentrations in the Lower Colorado
River range from approximately 750 mg/1 at Hoover Dam to about 850
mg/1 at Imperial Dam. Approximately 47 percent of these concentrations
derive from natural causes -- mineral springs and diffused pick-up
of salts by surface drainage -- and the remainder results from man's
development and use of the Basin's water resources. Planned and
proposed development of the water resources will further increase the
existing levels of salinity, and, by the year 2010, average salinity
concentrations are expected to be 990 mg/1 at Hoover Dam and 1220 mg/1
at Imperial Dam.
Generally, as salinity concentrations increase above 500 mg/1, the value
of water begins to diminish and the costs associated with its use begin
to increase. Increasing costs are incurred in water softening or
alternately, in the form of costs of corrosion, fabric wear and increased
use of detergents. They also include diminished crop yields, the
inability to grow certain high-value crops and the need for greater
amounts of leaching water to maintain salt balance in the root zone.
Because of such costs, increasing salinity levels in the Lower Colorado
River constitute a significant water quality problem. In fact, the
economic costs presently suffered by the water users of the lower
Colorado River amount to several millions of dollars annually, and
these will increase to over 15 million dollars per year by 2010 if
the predictions of future increases in salinity hold true.
The problem faced in water quality management in the Colorado River
Basin is one of improving existing mineral quality, or at least,
minimizing future salinity increases, particularly in the Lower Colorado
River where the effects of degraded mineral quality are most severe
and most costly. On first examination, salinity criteria appear ideally
suited for meeting either of these purposes. Such criteria would provide
concentration limits for total amount of salt and its constituents at
each of some dozen or two dozen points throughout the river system and
would set forth a plan of implementation and enforcement delineating
how and where sources of man-caused salinity would be controlled to
achieve compliance with these limits. Unfortunately, neither the
development nor the implementation of such criteria would be simple.
In fact, these criteria could significantly interfere with the development
and consumptive use of water for irrigated agriculture and other purposes.
The confounding problem in developing salinity criteria for the Colorado
River Basin, where irrigation is the principal source of man-caused
salinity, results from the consumptive use of water in crop production.
From 50 to 70 percent of the water applied in irrigation is consumed
by evapotranspiration. The remaining 30 to 50 percent returns to the
river system as irrigation return flow. This return flow usually contains
all of the salt load of the applied water, but in a smaller volume of
water. It may also pick up additional salts in the process of returning
to the stream. Accordingly, as water passes through an irrigation
cycle, its salinity concentrations are increased. Even if there were
no salt pick-up by irrigation return drainage and no non-beneficial
evaporative losses of water, irrigation would unavoidably increase
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salinity. To avoid this salinity increase would require nothing less
than a reduction of consumptive use, presuming that there exists no
economically feasible means of removing salts from irrigation return
flow. Such implementation of salinity criteria would severely conflict
with existing water rights, interstate compacts and international
agreements which have established the division and allocation of the
Basin's water resources. Two examples will serve to illustrate this
conflict.
Suppose that salinity criteria based on existing salinity levels were
to be set at several points along the lengths of the Colorado River
and its major tributaries. Unless the River's salt load could be reduced
markedly, compliance with these criteria would lock-in present patterns
of water use by precluding any additional consumptive use of the
Basin's waters. Future development of irrigated lands, as now planned
and proposed, would have to be halted and full use of the waters
allocated by compact to the Upper Basin States would have to be sacrificed.
In effect, these criteria would abrogate undeveloped water rights and
thereby would impose restrictions not commonly supposed to be the
function of water quality standards.
On the other hand, it would be possible to establish salinity criteria
throughout the Basin which would be based on existing salinity concentrations
plus allowances for future increases of salinity expected to result
from future consumptive use. However inviting this possibility might
seem, it must be noted that these criteria would fix the distribution
of future consumptive uses and thereby would predetermine the future
development of irrigation and other water uses. Accordingly, the setting
of these criteria would be impractical to the degree that future water
use cannot or should not be predetermined. Furthermore, it is far from
certain that such criteria can be established without imposing inequities,
even though their principal objective would be the achievement of an
equitable pattern of consumptive uses compatible with prevailing water
rights and compact divisions of water. The principal deficiency of
these criteria, however, would be their failing to protect and preserve
present water quality. This would be of greatest concern to current
water users of the Lower Colorado River who would suffer significant
degradation of their water supply because of the built-in allowances
for future increase in salinity.
These difficulties in developing salinity criteria do not mean that such
criteria cannot be derived or are inappropriate for controlling mineral
quality. It is technically possible to develop basin-wide salinity
criteria for the Colorado River Basin. Sufficient data on historical
stream flows and mineral quality, on flow-quality relationships and
on expected stream flows and quality under various levels of planned
or proposed water resource development are available for this purpose.
Accordingly, salinity criteria to preserve existing mineral quality
with or without allowances for various patterns of future development
can be formulated. The problem is not so much in this initial step of
establishing criteria, except for the difficulties in formulating
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equitable criteria, as in the subsequent step of implementing the
criteria. With respect to the appropriateness of salinity criteria, it
must be recognized that their purpose is the protection of legitimate
water uses, including irrigation uses. That the protection of existing
water uses in the Lower Basin requires a restriction of upstream water
uses is less a fault of these criteria than the limitations of nature.
If public policy is to preserve presently developed water uses, this
might require some restriction of new water uses, regardless of whether
salinity criteria or other regulatory devices are employed to effect
this policy. In this sense, salinity criteria are nothing but tools
to implement public policy and on this point an examination of how
such criteria could be administered and what implications they would
have for irrigated agriculture is in order.
Although there are a number of alternative measures which are discussed
later, there are only two direct approaches to implementing salinity
criteria within the Colorado River Basin: the regulation of consumptive
water uses and the desalination of waters whose salinity has been con-
centrated by consumptive use. To implement salinity criteria through
the regulation of consumptive uses would require adding quality to
quantity in determining water rights and interstate divisions of water.
The essential feature of this approach would be the reservation of
portions of river flows for the carriage of salt loads. This water
would remain in the river system and would not be allocated to con-
sumptive use. River flows in excess of salt carrying flows would be
available for division among the States and allocation to water users.
It is immediately apparent that such an approach would require considerable
modification of the institutional devices and procedures currently
employed to administer western water laws. Even so, these modifications
would be insignificant compared with the changes that would have to be
made in perfected water rights and interstate divisions of water.
In most cases, salinity criteria would restrict rights to consumptive
water use much more severely than existing water rights which are
wholly based on a division of available quantities of water. The
following example will illustrate this point.
At Hoover Dam, the Colorado River presently carries an average of
10.9 million tons of salt per year. If a salinity criterion of 800 mg/1
total dissolved solids were to be set at the Dam, an average annual
flow of about 10 million acre-feet would be required to carry this salt
load. Present average annual flows at Hoover Dam are about 11 million
acre-feet. Consequently, a salinity criterion of 800 mg/1 would permit
only 1 million acre-feet per year of additional upstream consumptive
use. This would deprive the Upper Basin of a substantial part of its
average annual allocation of 7.5 million acre-feet, as provided by
the Colorado River Compact, and would necessitate considerable readjust-
ment of prevailing interstate divisions of water and of existing water
rights within the Basin States. At the present time, for the reasons
illustrated in the foregoing example, the employment of consumptive
use restrictions to implement salinity criteria does not appear promising.
Nevertheless, eventual and perhaps partial use of such restrictions
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can and should be foreseen, whether these are specifically for the
purpose of implementing salinity criteria or are incidental to other
means of managing the Basin's water resource. A case in point is the
following. If it is assumed that 3000 mg/1 total dissolved solids is
the practical limit for usable water and that the last user on the
Colorado River is to enjoy water quality not exceeding this limit, then
to carry the River's 10.9 million tons per year salt load at this last
point of use will require an annual average river flow of about 2.4
million acre-feet. This would be water reserved from upstream consumptive
use for allocation to salt carriage and, in a sense, for wasting into
the ocean or into the Salton Sea. As this demonstrates, it is virtually
impossible to use the entire water resource of the Basin for consumptive
use if the last users are to enjoy any reasonable levels of mineral
quality. Consequently, restrictions on consumptive use for the reser-
vation of salt carrying flows are a practical necessity.
The other direct approach to implementing salinity criteria would involve
the desalting of wastes from consumptive use operations, including
irrigated agriculture. A percentage of the salt proportional to the
percentage of the water consumptively used would be removed so that
the water returned to the river system would have the same salinity
concentration as that withdrawn. Such an approach, if perfected, would
permit consumptive use of nearly all'of the water resource (some water
would be lost in brine disposal) and would eliminate the need to allocate
large river flows for carriage of salt load. Furthermore, this approach
would put salinity control on the same basis as the control of other
pollutants, by requiring the removal of salts as necessary to compensate
for loss of water in the water-use cycle. Unfortunately, this desalting
approach is presently encumbered by some severe economic and technical
constraints. Foremost among these is the high cost of desalting water.
Several recent studies conclude that large-scale desalting, usually
combined with thermal power generation, for the production of waters
for direct use will be economically feasible in the near future (1980 to
2000). However, the approach just described would require small-to-
medium scale desalting plants for waste water treatment, and it is
doubtful that such small scale plants will be economically feasible
in the near future. The technical problems include the necessity of
disposing of brines (these cannot be reintroduced into the river system
and must be disposed of in closed basins, deep geological formations
or the ocean) and the necessity of providing drainage systems for all
irrigated lands in order to collect return flows for treatment.
Notwithstanding these several liabilities, the desalting approach may
hold some promise for the future.
Recognizing the problems in formulating and implementing salinity
criteria, it seems appropriate to turn attention to other approaches
to salinity contol -- approaches which do not necessarily depend on
the establishment of criteria. Currently, there appears to be three
such approaches: the abatement of salinity at selected sources including
natural sources, the augmentation of river flows and the desalination
of waters for use. Measures to abate salinity at selected sources would
13
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seek to control salinity arising from causes other than beneficial
consumptive use. About 47 percent of the current levels of salinity
at Hoover Dam derive from natural causes -- the dissolution of the
salts in soils and geologic formations by natural surface and subsurface
flows. In some cases, these causes of salt loading can be controlled
by such methods as the plugging or suppression of mineral springs;
the diversion of stream flows around salt domes and other areas of
substantial salt pick-up; and the diversion of highly mineralized
surface flows into closed areas where they can be disposed of or used
for salt-tolerant uses. These several measures would eliminate a part
of the salt load presently reaching the Colorado River and thereby would
permanently reduce salinity concentrations in the River.
Another important cause of salinity is the salt pick-up by irrigation
return flow as it percolates through the soils enroute from the irrigated
land to the river system. This salt pickup accounts for about 26
percent of the salinity presently measured at Hoover Dam. This salt
load can be significantly reduced by (1) eliminating excess drainage
(over and above that required for leaching in maintaining salt balance
in the root zone); (2) the lining of canals and other conveyance
channels; (3) intercepting drainage at the bottom of the root zone and
conveying it to the river system, thus short-stopping unnecessary
subsurface travel and (4) selecting for new irrigation only those lands
which are underlain by low salinity soils. These measures would
reduce man's contribution of salt input into the river system and
thereby would serve to permanently reduce salinity. Preliminary
estimates indicate that a program of selected salinity source control
can achieve salinity reductions of up to 300 mg/1 at Hoover Dam. Such
a program would depend, in large measure, on irrigated agriculture.
The provision of structural control measures such as drains and canal
lining and the institution of improved water management practices would
be necessary to the full success of the program. Studies indicate,
considering the potential multiple benefits of such features, that
there is ample economic justification for the development of such measures
Augmentation of Colorado River flows would involve interbasin importation
of water, weather modification, water salvage or a combination of these
measures. Although these means are currently being proposed (and
studied except for interbasin importation) for the primary purpose of
meeting expected future water shortages, they would provide significant
water quality benefits. For example, 2.5 million acre-feet per year
of 300 mg/1 water delivered at Hoover Dam would reduce present levels
of salinity by about 75 mg/1. Consequently, flow augmentation is also
an attractive means for improving the mineral quality of the Colorado
River.
Finally, the desalting of water for direct use is an approach that may
be necessary to mitigate the consequences of uncontrolled or only
partially controlled salinity; that is, for providing acceptable water
supplies to replace those that are over mineralized. In addition, of
course, desalting also can serve to extend the Basin's water supply.
14
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Large-scale desalting combined with electric power generation is being
studied. Preliminary results indicate that this means of producing
high quality water may be economically feasible in the foreseeable
future (1980 to 2000). Certainly, desalting is a potential alternative
to be considered in solving the salinity problem of the Colorado River
Basin.
In conclusion, it is foreseen that the establishment of salinity criteria
for the Colorado River Basin will be difficult and may be a long time
in coming. A promising alternate and interim approach would be the
study and implementation of the three means of control just described.
The abatement of the increasing salinity of the Colorado River system
cannot afford further deferral particularly when the techniques to
achieve such abatement seem close at hand. A combination of salinity-
source abatement, flow augmentation and desalination can accomplish
immediate and needed results. And, if and when salinity criteria
can be and are established, these measurers can be easily and readily
factored into whatever devices are developed to implement and enforce
these criteria.
15
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PROBLEMS OF POLLUTION OF IRRIGATION
WATERS IN ARID REGIONS
by
H. B. Peterson, A. A. Bishop, and J. P. Law, Jr. —'
Historically, the users of irrigation water have been more concerned
with quantity rather than the quality being used. Now they must also
be concerned with the quality of water being used as well as that
which returns to the supply to be reused for other purposes or for
irrigation. We no longer have enough water to pollute and discard.
A hydrologic unit (river system with its drainage area and groundwater
basin, etc., and with its animal, plants, minerals, and people) can
be considered as a self-contained, hydro-pollution-purifying system.
The state of the system without man in it, if we can imagine such,
is natural and produces changes as a result of the dynamism within
it- In this natural or pristine state, changes in climate, vegetation,
geologic erosion, animal inhabitants, etc., are dynamic, having an
impact on the quality of the environment and resulting pollution in the
natural drainage from the area. The introduction of man into the system
with his power to create major changes and to introduce new or additional
pollution or treatment vectors in the waters of the system make it
imperative that the system be considered in its entirety and not from
the standpoint of a single use or source of pollution. Man superimposes
on the system, cities, transportation facilities, agriculture, irrigation
and drainage facilities, manufacturing plants, mining, timber harvesting,
range use, recreation, and other changes too numerous to mention. The
interactions of man, and the changes he produces, within the hydrologic
system is the major concern of this paper, particularly with respect
to irrigation and irrigation return flow.
Those who live in arid regions are intensely aware of the keen
competition for a limited water supply. The climate is conducive to
high evapotranspiration losses and a minimum of natural leaching. For
intensive crop production, irrigation is necessary in arid regions while
it is used only to supplement rainfall in more humid areas. Water
quality requirements for agriculture vary considerably with soils, crops,
and climate. The adverse effects of low quality on soils and plant
growth are related to the frequency and amount of water applied. Problems
associated with deteriorating water quality are, therefore, more
numerous and acute in arid and semiarid areas where the water require-
ments of the growing crop are satisfied almost entirely by irrigation.
— Professor and Head, Dept. of Agricultural and Irrigation
Engineering, Utah State University, Logan; and Research Soil Scientist,
Robert S. Kerr Water Research Center, USDI-FWPCA, Ada, Okla., respectively.
17
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Sources and Types of Pollution Affecting Water Quality
In the hydrologic cycle, it is natural for the pollution of a river
system to increase as the water moves toward the ocean where it is
purified by distillation and returned to the watershed. Enroute,
considerable purification takes place in the streams by oxidation and
biological degradation. Pollutants come from many sources before,
during, and after irrigation. They come from the animals; soils,
both irrigated and non-irrigated; fertilizers; pesticides; as well
as from industrial and municipal wastes. Some pollution is natural,
such as from mineral springs, lightning fixed nitrogen, etc. Even
a pristine river will show considerable quality change between its
source and the estuary. As indicated in Figure 1, the activities
of man to protect or improve the quality of water are counter forces
against natural pollution and man's normal tendency to pollute.
Our major concern, which is irrigation return flow, may be subject
to augmentation and further pollution from sources not connected
with irrigation; that is, precipitation, groundwater seepage, surface
runoff from urban areas, highways, and non-agricultural lands and
discharges from municipal and industrial sources which may commingle
with irrigation return flow. Quantity, quality, nature, and extent
of pollution from commingled waters have not been isolated or evaluated.
This will be difficult, but is essential in order to properly assess
the quality and pollution role of each water use affecting the total
water supply.
Natural Pollution
Of the many possible natural pollutants, salts and sediments are
likely of greatest concern to all users; however, under certain
conditions, animal waste, plant nutrient, and toxic elements may
become equally important. To irrigation agriculture and subsequent
users of return flow, salt and silt create the most difficult problems.
gait and sediments. Of the potential pollutants identified that may
enter into the water supplies, the one of greatest concern to irriga-
tion is salinity which is a natural product of geologic weathering.
It is released from contemporary weathering, mineral springs, and
seepage from areas of salt accumulation. Pillsbury (1) developed a
relationship between water production and salt yield on several western
watersheds. The salt production on streams varied from 0.1 ton per
acre foot (a.f.) on streams producing 1,000 a.f./sq. mile to over
5 tons/a.f. on streams producing only 1 a.f./sq. mile. The Bureau
of Reclamation has an active program to evaluate the quality of water
of several river basins. Some of the results are indicative of the
amount of salt loading resulting from natural sources, irrigation,
and others (2,3,4). As indicated in Table 1, the salt from natural
sources exceeds, in this instance, that from irrigation.
18
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CLEAN WATER
NATURAL POLLUTION
SALTS
SEDIMENTS
WILDLIFE WASTE
EVAPOTRANSPIRATION
WATER USE
CONSUMPTION--
CONCENTRATING
LOADING
ct
LL)
o:
\
NATURAL PURIFICATION
PUBLIC REACTION
CLEAN WATER ACT
QUALITY STANDARDS
WATER TREATMENT
REGULATION
DIRTY WATER — OCEAN
Figure 1. Forces of pollution with counter forces,
19
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TABLE 1
INCREMENTAL SALT CONCENTRATION ATTRIBUTABLE TO SPECIFIC SOURCES,
COLORADO RIVER AT HOOVER DAM (5)
Sources Total Dissolved Solids
(mg/1)
Natural
Diffuse Sources 274
Point Sources (mineral springs,
wells, etc.) 69
Irrigation
Consumption 88
Leaching 165
Municipal and Industrial Sources 10
Water Exports 22
Evaporation and Phreatophytes 97
725
There is little concrete information on the amount of sediment resulting
from wind and water erosion. (Erosion that would take place without
man's influence.) As previously noted, climate is a factor responsible
for some of the salinity and sodium problems found in the arid irrigated
areas of the West. It can, likewise, have effects on other pollution.
The amount and intensity of precipitation can influence the amount of
erosion and the accompanying sediment load of the flow. Many of the
watersheds are relatively unprotected by vegetative cover and are,
therefore, subjected to considerable erosion when moisture falls on the
land during high intensity storms. It is evident, however, that the
sediment load resulting from natural erosion is much more sporadic than
the salt load. In many of our arid basins only a small percentage of
the land surface is irrigated having a large watershed acreage to
produce salt and sediment loading of the river system. Van Denburgh
and Feth (6) estimated the annual solute erosion in 11 important river
basins. The wide range in tonnage was attributed to a complex of
causes, among which were differences in geology, climatic environment,
and the activities of man. Rates of solute removal were highest in
areas of abundant precipitation and runoff, in contrast to rates of
sediment removal, which are characteristically highest in basins subject
to 10-15 inches effective annual precipitation. Storage dams on most
river systems greatly modify the sediment problems.
20
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Nutrients, toxic elements, and organics. Nitrogen is added to the
system as a result of fixation by lightning and microorganisms, leaching
from nitrate deposits, and the mineralization of organic matter.
Phosphorus enters the system as a result of mineralization or organic
matter, such as non-agricultural plant and animal wastes, release from
sediments, and solution of natural phosphate minerals. Toxic elements,
such as boron, enter the supply from natural deposits, usually by way
of mineral spring waters.
Agricultural Pollution
The emphasis of the current discussion is on the effects of irrigation
on water quality. As such, it is not possible to completely separate
the pollution attributed to irrigation agriculture from the non-irrigated.
It is also worthwhile to remember that while increasing salt concentration,
the irrigation process may remove other pollutants introduced into the
water supply from cities, farms, and industries. For example, nutrients
and organic wastes deposited on agricultural land with irrigation water
may be used by the crop, fixed by the soil, or degraded, so they are
not contained in the irrigation return flow.
Salts and sediments. Salt pollution from agriculture is limited almost
entirely to irrigated agriculture. Irrigation implies the extraction
of almost pure water by the plants from the water supply with a resulting
inevitable concentration of those dissolved solids which are characteristic
of all natural water supplies. Whereas other uses add something to the
water, irrigation basically removes water, thereby concentrating the
salts. Irrigation may also add substances by leaching natural salts or
other materials from the soil or washing them from the surface. Irrigation
return flow is a mechanism, as illustrated in Figure 2, by which the
concentrated salts and other substances are conveyed from irrigated
agricultural lands to the common stream or underground supply. It includes
bypass water, seepage, deep percolation losses, and tailwater runoff.
The pollution effects of irrigation are different for each specific
area or condition and depend on the concentration in the irrigation water,
the proportion of the water leaching through the soils to that applied,
the number of times the water is reused, and the amount of leaching
from areas having residual salts. Salty groundwater and salt bearing
shales serve as an abundant source of salt that may be loaded into the
system both directly and indirectly by irrigation. It is this loading
potential that makes it most difficult to estimate the salt concentration
in the drainage water and the amount of salt loading that may be expected
along a river system. This is also the reason why a salt balance for
a given area is of little value as evident by the equation:
21
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Application of fertilizers,
herbicides, and pesticides
to soil or plants
KJ
ro
Evapotranspiration
of relative pure.
water |
Concentration of
salts in the soil
solution due to
2vapotranspiration
/
'','
'/
Precipitation
(relatively
pure water)
Nutrients etc.
used by plants^
/
"•?.
/•
Fertilizers, wastes,
herbicides, etc.,
digested, degraded, or
precipitated within the
soil profile
Surface runoff with
sediment, residues,
and dissolved
solids
/'
W t
. Total^
/ water
i added
*--,—•
* *
Irrigation water
with various
amounts of
dissolved
solids
sewage
wastes
fertilizers
etc
Deep percolation
and drainage
Groundwater recharge
•\
\
Figure 2.
Wastes
Industrial
Municipal
Agricultural
Recreational
Effect of the water-plant-soil complex on the quantity and quality of
irrigation return flows.
Return flow from agricultural lands
with salts, residues, pesticides and
other pollutants
-------
S +S+S-S - S =0
iw w r ppt dw
where:
S = salt In the irrigation water
iw
S = salt from contemporary weathering
w
S = residual salts
r
S = salt precipitated
PPt
S = salt in the drainage water
dw
There may be a balance for a basin, but much of the outgoing salt can
come from the reserve rather than from the soil being irrigated.
The concentration of the salt in the soil solution will usually be
in the range of 4-10 times the concentration of the irrigation water; and
hence, the solution draining from the soil profile may be much higher
in salt content than the water applied. Where the drainage from the
root zone is impeded by a high water table, the concentration of the soil
solution may be many times the concentration of the irrigation water.
Fortunately, the concentration of salt in many irrigation waters is so
low that the leachate under normal irrigation practice is much less
concentrated than theoretically possible, and, when return to the
stream or the groundwater body, the effect on the quality of the resulting
water is not serious. The average increase in concentration in return
flow is usually in the range of 2.5 to 7 times that of the source water.
The scope of the problem of return flow is, therefore, limited from a
practical standpoint to those areas and conditions where water quality
becomes degraded to a point where it constitutes a nuisance, a hazard,
or is of no value for further use.
Irrigated soils of the United States are scattered throughout, but
the major areas are in the 17 western states. Within these, the areas
most adversely affected by salt in the irrigation return flow are those
in the lower reaches of the larger river systems of southwestern United
States; those areas in the Lower Basin of the Colorado River, the Gila
and Salt Rivers of Arizona, the Rio Grande in New Mexico and Texas, the
San Joaquin River in California, and similar streams. In all of these
river basins, there is a progressive deterioration in water quality as
it flows downstream.
23
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Nutrients and animal wastes. To understand the problem of pollution
of waters with plant nutrients from fertilizers, it is necessary to
understand the factors which affect the forms and solubilities of the
plant nutrients and the manner in which these are transported. The
nutrients of major concern as pollutants are nitrogen and phosphorus.
Nitrate in the drainage water can originate from rain, dust, soil,
organic matter, manures, an accumulation in the soils prior to irrigation,
fixed by microorganisms, fertilizers, and from the wastes in urban
and industrial runoff. It is removed from the soils by crops, de-
nitrification, and in drainage waters. It is, therefore, difficult
to determine the source of the nitrate in drainage waters.
The presence of plant nutrients in surface water is often attributed
to a seemingly large tonnage of fertilizers applied to the land for
maximum crop production. On much of the land, the amount of fertilizer
applied is less than that used by the crop. A low average application,
however, does not exclude the possibility of excessive amounts being
used on a portion of the acreage. For some high value crops, such
as celery, where the common practice is to make heavy applications of
fertilizers, particularly nitrogen, coupled with frequent irrigation,
it is likely that considerable nitrate may be leached with the excess
water and appear in the waters of the drainage system. Doneen(8)
concluded from a careful study in the San Joaquin Valley of California
that in one field receiving heavy application of fertilizer a large
portion of the nitrate in the drainage water was from the fertilizer.
In two other fields recently drained, he could not come to the same
conclusion because nitrates had been accumulating in the subsoil and
groundwater for a long period of time. It is estimated that from
combined sources, the nitrate-nitrogen content of the water in the
San Luis drain is expected to be of the magnitude of 20 mg/1 (9).
Phosphate fertilizers can increase the phosphorus content of drainage
water in several ways. Percolating water passing through a heavily
fertilized sandy soil low in fixing capacity will carry soluble
phosphorus into the drains. Fertilizers applied to the surface of
soils tend to stay near the surface and saturate the "fixing" sites.
When the fertile surface particles are eroded by wind or surface runoff,
the phosphorus is carried with the sediments into the water system.
There it equilibrates with the phosphorus in the water and may increase
the concentration in solution unless the content of the water is at
or above the equilibrium concentration. Biggar and Corey (10) speculate
that runoff water in contact with fertile surface soils can pick up
soluble phosphorus as it moves over the surface of the land, and the
concentration of the runoff water might range up to a few tenths of a
mg/1. Phosphate fertilizer can also have a more indirect effect.
It can stimulate plant growth, and then parts of the plant, such as
dried leaves, can be carried by wind or water into the drainage water
where the plant material is mineralized by microorganisms, with the
resulting accumulation of soluble orthophosphate in the water.
24
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Johnston et al. (11) studied N and P losses In tile drainage effluents
from H number of tile drainage systems in irrigated areas in the San
Joaquin Valley of California. A number of cropping practices, with
crops (cotton, alfalfa, rice), fertilizers and irrigation water
applications as variables were involved in the study. Initial tile
effluent analysis in a previously unirrigated noncropped area showed
an N concentration of 1 mg/1. Another system that had been cropped
to alfalfa and had a low discharge over the period of a year yielded
a range of N between 2.0 and 14.3 mg/1. On systems where high rates
of N fertilizer were applied, the concentrations ranged up to 62.4 mg/1.
In the systems reported, the range of concentrations of nitrates
went from 1.8 to 62.4 mg/1 with a weighted average of 25.1.
Both nitrogen and phosphorus can be carried directly into the surface
drains with the tailwater from fields where the fertilizer is being
applied in the irrigation water. Another likely source of nutrient
pollution is the animal wastes in the runoff from pastures and feeding
lot operations being included in drainage waters. Pollution can also
come from non-irrigated agricultural land. The runoff water would be
expected to contain very small amounts of salts, and other pollutant
loading would be similar to the runoff from irrigated land. Erosion,
with the resulting sediment load, plant nutrients, and pesticides would
be sporadic and greatly influenced by the intensity of precipitation.
The rapid growth of large animal-feeding operations has resulted
in a tremendous increase in the potential pollution hazard from domestic
animal wastes. A recent report (12) states: "Animal wastes in this
country probably exceed wastes from any other segment of our agricultural-
industrial-commercial-domestic complex." The Department of Agriculture (13)
has estimated that over 1.5 billion tons of animal wastes are produced
annually, one-third of which is liquid, and as much as 50 percent
coming from concentrated production operations. From the USDA
population equivalent values, it is evident that a feedlot operation
with 10,000 cattle will produce wastes equivalent to a city of 164,000
people. A city of this size will use over 8 million gallons of water
per day to carry its wastes while the feedlot seldom uses large
quantities of water to carry the wastes. Untreated municipal sewage
may have a biochemical oxygen demand (BOD) of about 100 to 400 mg/1.
Runoff from cattle feedlots produced by rainfall is a very high
strength organic waste and may have a BOD content as high as 10,000 mg/1
(13,14) depending on rainfall amount and intensity, antecedent moisture
conditions, slope and surface conditions of lot, degree of deterioration
of wastes, and other factors. It has been further demonstrated that
feedlot runoff is a source of high concentrations of bacteria normally
considered as indices of sanitary quality (14). Other pollutants
arising from animal wastes are the nutrient compounds of nitrogen and
phosphorus, and mineral salts. It is difficult to predict the magnitude
of the pollution problem in drainage systems induced by animal wastes.
It is safe to assume that there is a considerable amount of such pollution,
and that the drainage lines and ditches provide conveyance routes to
the waterways.
25
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Pesticides. Pesticides are recognized potential pollutants in water.
As with nutrients, the origin is not restricted to agricultural usage.
Pesticides are used in the cities, industrial areas, in forests, as
well as on the farmland. They can enter the water by direct application
from drift during application or be washed from adjacent lands adsorbed
to the eroded sediments. In a similar manner, pesticides can also
pollute the waters of irrigation return flow. There is nothing
unique about pesticide pollution and irrigation, except perhaps where
pesticides are used to control weeds and insects along irrigation canals
and open drains.
Many of the pesticides used are sorbed chemically and physically by
the soil particles. Those thus sorbed are not likely to enter subsurface
waters. LeGrand (15) reporting on movement of pesticides in soils
suggests that it is likely that most all pesticides in streams result
from overland flow. Nicholson (16) in discussing pesticide pollution
control states:
The two principal sources of water pollution by
pesticides are runoff from the land and discharges
of industrial waste, either from industries that
manufacture or formulate pesticides or from those
that use these compounds in their manufacturing processes.
Less important causes of pollution are (i) activities
designed to control undesirable aquatic life, (ii) care-
less use of pesticides, and (iii) occasional accidents
in transportation.
Johnston et al. (17) analyzed drainage effluent from systems located
on irrigated land in the San Joaquin Valley of California. On
experimental areas, the insecticides DDT, Parathion, and Lindane
had been added. Only relatively small quantities of chlorinated
hydrocarbon residues were found in effluent from open drains where
both surface and subsurface drainage waters were collected. Traces
of residue were found in the irrigation water applied to tile drained
farms. When the concentration factor was considered, that is, depth
of irrigation water applied/depth of drainage water removed, on a
unit basis, the total quantity of insecticide residue in tile drainage
effluent did not exceed and was generally less than the total quantity
of residue applied in the irrigation water. Tailwater, or surface
runoff, contained from 7 to 12 times as much residue as the applied
water when DDT was applied to the land and as much as 85 times more
residue than the irrigation water when Lindane was applied to the land.
Relatively large concentrations of residue were found in the surface
soil of the area studied.
As a generalization, it appears that the chlorinated hydrocarbons,
such as DDT, persist in soils (18,19) and do not move in appreciable
concentrations through the soils and into drainage effluent as ground-
waters. Movement is primarily with suspended sediment, either organic
26
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or inorganic materials in streams and open drain flow. The thiophosphates,
such as Parathion, decompose rapidly and do not persist in soils or water.
Pesticides can be transported in the air while applications are being
made and be deposited in waters remote from the area of application (20).
Wind can remove surface soil to which pesticides are adsorbed and be
deposited by rain or the settling dust.
Faulkner and Bolander (21) have found large numbers of nematodes
including plant parasites in irrigation and drainage waters. There
is no indication yet as to the nature and magnitude of any pollution
problems that might accompany the treatment of water for the control
of nematodes.
Indirectly, pesticides may add other pollutants to soils and water.
The organic phosphorus insecticides and raiticides readily decompose
in soil and release soluble phosphorus. Other organic pesticides are
composed of compounds containing mercury, zinc, manganese, copper,
chromium, cadmium, and tin. When the organic compounds are decomposed,
the metal ions are released.
Municipal and Industrial Pollution
The occurrence of municipal and industrial wastewaters in water supplies
used by irrigated agriculture may be the result of incidental discharges
into a common receiving water subsequently used for irrigation or from
direct, intentional application of such wastewaters as a prime source
of supply. In either case, the nature and concentration of any constituent
that may be considered as a potential pollutant will depend upon the
specific characteristics and origin of the wastewater; that is, whether
(a) of purely domestic origin, (b) a combination of domestic and
industrial origin, or (c) essentially an industrial discharge. In
addition, the characteristics of the wastewater may be ameliorated by
the degree of treatment and/or dilution afforded the effluent.
Municipal effluent. Several studies of mineral increments from
community use have been made, and an example of data reported is shown
in Table 2. In another study (22), the salt pickup in the sewage
system of the City of Los Angeles was 635 mg/1. The most important
potential pollutants in municipal wastewater effluents affecting an
irrigation supply would include total dissolved solids, sodium, chloride,
and boron. Even one use of water could increase the boron content
above the tolerance limits for some crops. Recycle a few times and the
boron content would almost certainly be too high for most crop plants.
Industrial wastewaters. Characterization of industrial wastes is
exceedingly difficult for several reasons: (a) the numerous different
water using and waste producing variety of industries, (b) the wide
range and spectrum of potential pollutants that are involved, sometimes
27
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TABLE 2
MINERAL INCREMENTS IN DOMESTIC WASTEWATER
FOR 15 CALIFORNIA COMMUNITIES (23)
Analysis
(mg/1)
Dissolved Solids
Boron (B)
Percent Sodium (percent)
Sodium (Na)
Potassium (K)
Magnesium (CaCO-j)
Calcium (CaC03)
Total Nitrogen (N)
Phosphate (PO^)
Sulfate (304)
Chloride (Cl)
Maximum
Range
1200
3.8
42
290
22
110
250
42
50
75
550
Normal Range
Domestic Sewage
100-300
-1-.4
5-15
40-70
7-15
15-40
15-40
20-40
20-40
15-30
20-50
varying significantly within the same industry, and (c) the paucity of
factual data available on the volumes and pollutional characteristics
of many industrial wastes. An example of important water using industries
and associated pollutional characteristics of the wastewaters is shown
in Table 3.
Potential pollutants of industrial origin that are of particular concern
to irrigated agriculture include: (a) total dissolved solids, sodium,
and chlorides, (b) boron, (c) heavy metals, (d) pesticides, (e) radio-
activity, and (f) numerous organics.
Recreational Wastes
Pollution from recreational activities are probably the least delineated
of all sources. It may not greatly influence the quality for irrigation,
but it certainly does influence the quality of water for other uses.
Man's activity is responsible for human wastes at campsites and in-
directly from summer homes. Fishing, boating, and production of wild
game all contribute. The building of roads, trails, homesites, etc.
expose the soil to erosion which may well be the most serious form of
pollution attributed to recreation.
Quality Changes from Irrigation
The only certain change in water quality caused by using water for
irrigation is the increase in the concentration of soluble salts. How
much this change will be depends on variables at each specific location.
28
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TABLE 3
SOME SIGNIFICANT CHEMICALS IN INDUSTRIAL WASTE WATERS1(24)
Chemical
Industry
Acetic acid
Alkalis
Ammonia
Arsenic
Chlorine
Chromium
Cadmium
Citric acid
Copper
Cyanides
Fats, oils, grease
Fluorides
Formalin
Hydrocarbons
Hydrogen peroxide
Lead
Mercaptans
Mineral acids
Nickel
Nitro compounds
Organic acids
Phenols
Silver
Starch
Sugars
Sulfides
Sulfites
Tannic acid
Tartaric acid
Zinc
Acetate rayon, pickle and beetroot manufacture.
Cotton and straw kiering, cotton manufacture,
mercerizing, wool scouring, laundries.
Gas and coke manufacture, chemical manufacture.
Sheep-dipping, fell mongering.
Laundries, paper mills, textile bleaching.
Plating, chrome tanning, aluminum anodizing.
Plating.
Soft drinks and citrous fruit processing.
Plating, pickling, rayon manufacture.
Plating, metal cleaning, case-hardening, gas
manufacture.
Wool scouring, laundries, textiles, oil
refineries.
Gas and coke manufacture, chemical manufacture,
fertilizer plants, transistor manufacture, metal
refining, ceramic plants, glass etching.
Manufacture of synthetic resins and penicillin.
Petrochemical and rubber factories.
Textile bleaching, rocket motor testing.
Battery manufacture, lead mining, paint
manufacture, gasoline manufacture.
Oil refining, pulp mills
Chemical manufacture, mines, Fe and Cu pickling,
DDT manufacture, brewing, textiles, photoengraving,
battery manufacture.
Plating.
Explosives and chemical works.
Distilleries and fermentation plants.
Gas and coke manufacture, synthetic resin
manufacture, textiles, tanneries; tar, chemical
and dye manufacture, sheep-dipping.
Plating, photography.
Food textile, wallpaper manufacture.
Dairies, foods, sugar refining, preserves, wood
process.
Textiles, tanneries, gas manufacture, rayon
manufacture.
Wood process, viscose manufacture, bleaching.
Tanning, sawmills.
Dyeing; wine, leather and chemical manufacture.
Galvanizing, plating, viscose manufacture,
rubber process.
Reproduced by permission Butterworths. "River Pollution.
2: Causes and Effects," Klein.
29
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Some of these are: (a) the proportion of the water consumed, this is
dependent on irrigation efficiency, number of times the return is
reused, etc., (b) the amount of residual salts leached from the soil
profile, (c) the amount of salt carried into the drainage system by
seepage from canals, storage reservoirs, etc., and (d) the amount of
salt loading of drainage effluent from other unidentified sources.
The probable changes in salinity and other pollutants are indicated
in Table 4. These are the changes that are likely to occur when water
carrying the pollutants comes in contact with soil surface or passes
through the profile. As noted, the probable effects are very different
depending on whether or not the water passes through the soil and whether
or not the concentration is high in the original water.
Problems of Irrigation Agriculture
The users are concerned with the overall degradation of water quality
and the presence of specific pollutants that can adversely affect the
value of water for irrigation as well as for other uses. Regardless
of the source of pollutants, water quality should be evaluated for
potential hazards to crops and soils before being used. The harmful
effects of salt and the specific effects of sodium, chloride, arsenic,
boron, and the heavy metals have been well established (25).
Different pollutants have very diverse and changing effects on the
value of water. This is illustrated in Figure 3. Salts generally
decrease the value more or less in proportion to the concentration
increase; however, there are broad critical ranges where the user is
forced to change the type of crop, and then there may be a sharper
value decline for a given increment of salt. This can continue until
at some concentration the water can no longer be used for irrigation and
must be disposed of or treated. At such a concentration, there is a
change from a small positive value to perhaps a large cost depending
upon the method of treatment or disposal.
The effects of other pollutants on value may be more nearly as indicated
for some specific toxicants. Whether it be the salt concentration or
the amount of some other pollutant that makes treatment or disposal
necessary, there is then an effect on the value of plant nutrients
which may abruptly change to a liability. The situation in the San
Joaquin Valley of California is an example where there is a large cost
for disposal of return flow waters. One cost is for removal of plant
nutrients before the water can be discharged into San Francisco Bay
and the other in the construction of the San Luis Drain to convey the
water to the Bay (26,27). There are, of course, in some instances less
costly alternatives, such as discharge into a water fowl refuge where it
may have some value or directly into a dead sea or lake where the water
may have limited value but is not necessarily a liability.
30
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TABLE 4
PROBABLE CHANGES IN QUALITY AS A RESULT OF IRRIGATION
Quality
Factors
Salts
(TDS)
Sodium and
Chloride Ions
Nitrate
Phosphate
Pesticides
Pathogens and
other
Organisms
Sediments and
Colloids
Organics
Heavy Metals
Sewage
Effluent
Irrigation Return Flow
Surface
Not greatly different from sources
Relatively unchanged.
More likely a slight increase than a
decrease and highly variable.
Content may increase, but closely
correlated with erosion of fertile
toj>soil.
Highly variable content. Surface
waters subject to polluting. Likely
associated with amount of erosion.
Variable and may increase or decrease.
Often more than in source but may
be less—highly variable.
Manures, debris, etc., likely to
increase
Kinds and amounts are variable. Likely
to be greater than in subsurface flow.
Not greatly changed except by filtering
and oxidation effect of crops if
sprinkled .
Subsurface Drainage
Concentration increased usually 2-7 times.
Depends on amount in the supply, number of
times reused, the amount of residual salts
being removed, and the amount from non-
agricultural sources.
Both proportions and concentration likely
to increase.
Likely to decrease if the content in irri-
gation water is high and increase if amounts
are low. Greatest hazard from heavily ferti-
lized porous soils over irrigated.
Decrease if considerable in source. Not
likely to greatly increase.
A reduction in many instances. Concentra-
tions likely to be low.
Low content with a likely reduction in most
all pathogens. Other organisms may increase
or decrease.
Little or no sediment or colloidal materials
in the flow.
Most oxidizable and degradable materials to
decrease .
More likely to decrease in concentration.
Concentration of all pollutants reduced
except common soluble salts.
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NUTRIENTS.
CO
O
D_
o
01
OL
01
o
uu
01
CRITICAL LEVELS
SPECIFIC TOXICANTS
V /
TREATMENT
OR
DISPOSAL
UJ
CONCENTRATIONS
Figure 3. The effect of different kinds of pollutants on the value
of water for irrigation.
32
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of Return Flow
The concentrating of some pollutants, such as salts, is an inescapable
consequence of consumptive use of irrigation water. There are, however,
possibilities for regulating the concentration. On the other hand,
the loading of a stream with pollutants can, in some instances, be
more nearly controlled.
Concentrating Salts
Even though it is not possible to prevent concentrating salts, it is
theorectically possible to regulate the concentration of the return
flow. This is by some form of dilution of which there are several:
(a) regulating the amount of applied water that is returned to the
system (regulating the amount and time of leaching), (b) importing
water for direct dilution or alternative uses, (c) increase the water
supply by weather modification, and (d) desalt some of the water and
use for dilution.
Such activities as increasing the supply by weather modification and
desalting introduces new problems. More water by increasing precipitation
will undoubtedly bring more salt and sediment from the watershed.
This will depend on where and how the increase comes. Brine disposal
is a problem created when water is desalted somewhere along a river
system.
Loading Effects
Considerable of the salt loading effects can be reduced by diverting
salty water from the supply. This may include diverting natural
salty water as well as seepage waters that have accumulated salt.
Establishing a drainage network whereby most of the drainage water
is from the soil profile offers some hope for reducing loading. In
such a system the soil would be managed so as to keep the salty groundwater
below the active drains and, thereby, reduce the amount of loading.
Lining of canals, ponds, etc., to prevent seepage and leaching from
non-irrigated soil is another practical method. Exclusion of lands
containing appreciable amounts of residual salts or pre-leaching of
such soils and diverting the drainage waters also prevents the addition
of salt to the system. Drainage waters from new lands usually contain
the greatest amounts of salts because of the salt in the profile not
previously exposed to leaching water.
The loading of pesticides, plant nutrients, and sediments can largely
be controlled by preventing the erosion of the top soils and runoff.
We recognize that there will be spillage and accidental discharge as
well as movement of some soluble pollutants through the soil and into
the drainage waters.
33
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The identification of kinds, amounts, and sources of pollutants and utilizing
the mentioned control methods may appear relatively simple. This would not
be a proper evaluation of the situation. The salinity problem alone is
highly variable and as expressed by the Bureau of Reclamation:
Each irrigated area has a different effect on
quality depending upon properties of the soils and
substrata in the drainage area, number of years the
land has been irrigated, number of times return flow
is reused, nature of the aquifers, rainfall, amount of
dilution caused by surface wastes, temperature, storage
reservoirs, vegetation, and types of return flow
channels.
It is our opinion that loading of heavy metals and boron by industry
and domestic users offers major hazards to irrigation agriculture. There
is no known method of detoxifying the soil once critical levels of heavy
metals have been reached. Boron compounds have many uses; and hence,
there are many sources of contamination. It is very harmful to plants at
low concentration--levels well below the tolerance levels to man and
animals
Beneficial Effects
Not all of the effects on the quality of return flow are adverse.
The soil can improve the quality by: (a) filtering suspended solids,
(b) removal of heavy metals, pesticides, and phosphate by chelation,
sorption and/or precipitation, (c) degrading detergents, wastes and
other organics, and (d) by providing the death time for harmful micro-
organisms. Such benefits can be used to counter the disadvantages
resulting from the consumption of water. Eliminating irrigation within
a basin may reduce some of the salt loading and concentrating of the
salt, but certainly would not eliminate the salt problems, and it could
increase some of the problems created by other pollutants.
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REFERENCES
1. Pillsbury, Arthur F., and Harry F. Blaney, "Salinity Problems
and Management in River Systems," ASCE 92(IRI):77-90, March 1966.
2. lorns, W. V., C. H. Hembree, D. A. Phoenix, and G. L. Oakland,
"Water Resources of the Upper Colorado River Basin Basic Data,"
USGS Prof, paper 442, 1964.
3. U.S. Dept. of the Interior, "Quality of Water, Colorado River
Basin," Progress report No. 3, January 1967.
4. U.S. Dept. of the Interior, "Quality of Water, Colorado River
Basin," Progress report No. 4, January 1969.
5. Federal Water Pollution Control Administration, "The Cost of
Clean Water," Vol. II, Detailed Analysis, USDI, 1968.
6. Van Denburgh, A. S., and J. H. Feth, "Solute Erosion and Chloride
Balance in Selected River Basins of the Western Conterminous
United States," Water Resources Research, Vol. 1:537-541, 1965.
7. Doneen, L. D., ed., "Proceedings, Symposium on Agricultural
Waste Waters," Report No. 10, Water Resources Center, University
of California, Davis, April 1966.
8. Doneen, L. D., "Effect of Soil Salinity and Nitrates on Tile
Drainage in the San Joaquin Valley of Calif.," Water Science
and Engineering Papers 4002, Dept. Water Science and Engineering,
University of California, Davis, December 1966.
9. Grinstead, R. R., et al., "Feasibility of Removal of Nitrates from
San Luis Drain Waters by Ion Exchange," A report to the U. S.
Bureau of Reclamation, Dept. of the Interior, by the Dow Chemical
Company, August 26, 1968.
10. Biggar, J. W., and R. B. Corey, "Agricultural Drainage and
Eutrophication," International Symposium on Eutrophication,
Madison, Wisconsin, June 11-16, 1967.
11. Johnston, William R., F. I. Ittihadieh, and Arthur F. Pillsbury,
"Nitrogen and Phosphorus in Tile Drainage Effluent," Soil Science
Society of America Proceedings, Vol. 29(3):287, 1965.
12. The Secretary of Agriculture, and the Director of the Office of
Science and Technology, "Control of Agriculture-Related Pollution,"
A report to the President, 102 pages, Washington, D. C., January 1969.
13. Wadleigh, C. H., "Wastes in Relation to Agriculture and Forestry,"
USDAMisc. Publ. No. 1065, Washington, D. C., March 1968-
35
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14. Miner, J. R., R. I. Lipper, L. R. Fina, and J. W. Funk, "Cattle
Feedlot Runoff--Its Nature and Variation," Jour. WPCF, Vo. 38,
No. 10, pp. 1582-1591, October 1966.
15. LeGrand, H. E., "Movement of Pesticides in the Soil," Pesticides
and Their Effects on Water Symposium Special publication, Vol.
8:71-77, American Society of Agronomy, Madison, Wisconsin, 1966.
16. Nicholson, H. Page, "Pesticide Pollution Control," Science,
Vol. 158:871-876, 1967.
17. Johnston, William R., F. T. Ittihadieh, Kenneth R. Craig, and
Arthur F. Pillsbury, "Insecticides in Tile Drainage Effluent,"
Water Resources Research, Vol. 3(2):525-537, 1967.
18. Nash, Ralph G., and Edwin A. Woolson, "Persistence of Chlorinated
Hydrocarbon Insecticides in Soil," Science, Vol. 157:924-927,
August 25, 1967.
19. Texas A&M University, "Water for Texas," Water Quality and Chemicals
Conference, Proceedings 9th Annual Conference Water Resources
Institute, November 1964.
20. Weibel, W. R., R. B. Weidner, J. M. Cohen, and A. G. Christiansen,
"Pesticides and Other Contaminants in Rainfall and Runoff," Jour.
AWWA, Vol. 58(8):1075-1084, August 1966.
21. Faulkner, Lindsey R., and W. J. Bolander, "Occurrence of Large
Nematode Populations in Irrigation Canals of South Central Washington,"
Jour- International Nematological Research, Vol. 12:591-600,
(A-011-WASH), 1966.
22. Meron, Aharon, and Harvey F. Ludwig, "Salt Balances in Groundwater,"
Jour. Sanitary Engineering Div., ASCE, pp. 41-61, June 1963.
23. Water Pollution Control Board, "Studies of Waste Water Reclamation
and Utilization," State of California, Publ. No. 9, 1954.
24. McGauhey, P. H., "Engineering Management of Water Quality,"
McGraw-Hill Book Co., New York, 1968.
25. Federal Water Pollution Control Administration, "Water Quality
Criteria," Report of the National Technical Advisory Committee
to the Secretary of the Interior, 215 pages, Washington, D. C.,
April 1968.
26. Department of Water Resources, "San Joaquin Valley Drainage
Investigations," State of California, Sacramento, Bulletin 127,
January 1965.
27. Berry, William L., and Edward D. Stetson, "Drainage Problems
of San Joaquin Valley," Jour. Irrigation and Drainage Div., ASCE,
Vol. 85 (IRI):97-106, September 1959.
36
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WATER QUALITY REQUIREMENTS AND RE-USE OF WASTEWATER EFFLUENTS
by
Stanley J. Dea I/
Although the Federal role in water pollution has evolved over a 65'
year period, there has not been a very long history of interest or
concern with the subject of wastewater reclamation. In fact, many of
the primary and secondary sewage treatment processes in use today were
known some fifty years ago, and it was not until the early 1960's
that the degradation of our waters as a resource became a national issue.
This awareness, occasioned through the accumulated and continuing
effects of rapid economic and population growth, culminated in the
passage of two very important and far-reaching laws -- (1) the Water
Quality Act of 1965 which required that standards of water quality be
established, implemented and enforced for all interstate and coastal
waters of the United States, and (2) the Clean Water Restoration Act
which provided for the Federal Government's participation in financing
needed treatment plants and in undertaking, fostering and sponsoring
needed research, development and demonstration efforts.
Under these laws, the 50 states have proceeded to establish standards
of water quality for each of their interstate waters, and many States
have further chosen to establish such standards for their intrastate
waters as well. The standards are not uniform across the country, but
vary as you might expect according to individual circumstances relating
to climatic zone, hydrogeologic factors, present water quality, and
a host of other location-related variables. There are only two uniform
guiding principles: (1) the standards for any given river, or stretch
of river, must spell out the beneficial uses which the public expects
to make of the water resource (i.e. recreation, fishing, municipal or
industrial water supply, etc.) and (2) the criteria chosen to support
such uses (i.e. dissolved oxygen content, temperature, pH, etc.) must
be adequate to protect and in fact enable such uses to be made.
The establishment of river uses and criteria has profoundly affected
the philosphy of water quality management on a national scale. This
has been particularly true in the case of wastewater treatment for
pollution control. In the United States, to date, treatment requirements
have been usually expressed as removal efficiencies. The removal
efficiencies in turn have been almost directly related to specific
treatment operations or processes. However, the stated purpose of the
Water Quality Act of 1965 is to "enhance the quality and value of our
water resources." Treatment requirements become more meaningful when
— Formerly Chief, Agricultural Pollution Control Section;
Office of Research and Development, Federal Water Pollution Control
Administration, U. S. Department of the Interior, Washington, D. C.
37
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They are expressed in terms of quantities of impurity when the objective
is attempting to protect water quality. Therefore, requirements are
moving to the concept of specifying the total quantity of impurity which
may be discharged into receiving water. The means of accomplishing
that quantity are being determined by the industry or the municipality,
because in most cases, it is this quantity which impairs the quality
of the stream.
It is now recognized that specification of the quantity of impurities
is the only means to maintain the quality of the receiving water where
there might be an increase in wastewater flow. Thus, as population
grew or industrial activity increased, more effective treatment or
control devices would have to be installed in order to meet the established
quantity requirement.
Brief reflection upon the dual problems of water supply (quantity)
and water pollution (quality) should manifest the inseparable bond
which exists between them. If water were used only once and then
disposed of, any degree of water quality degradation would be incon-
sequential. But, except in rare cases, reuse does occur in some form.
Gone are the days when man can readily depend upon the hydrologic cycle,
upon dilution, or upon natural purification to restore the quality and
quantity of his water source. Thus, when one user degrades the water
quality so as to deny reuse to the next user, the latter's water supply
is diminished by that amount.
By restoring the quality of waste effluents to higher and higher degrees,
the point is reached when they can be deliberately and directly, or
indirectly, reused for any beneficial purpose, even for potable water.
In addition to alleviating pollution, the renovation of wastewater can
simultaneously augment the water supply. Thus the concept of complete
water renovation solves the problems of water pollution and water supply,
simultaneously.
Presently, heavy reliance is placed on secondary treatment of municipal
wastes and its equivalent for industrial waste to achieve and maintain,
in a reasonably short time frame, the quality of water as it is specified
in the standards for the receiving water. The standards for each State
include a so-called "Implementation Plan," which is usually a listing
of specific needs to install new secondary sewage treatment plants or
upgrade and improve existing primary plants for given locations and
in a given time frame. At some locations, however, plans of the States
call for primary treatment only; at others, even secondary treatment
will not suffice to restore quality, or to maintain it in the face
of expected future economic and population growth, and the plans call
for the installation of tertiary, or "advanced waste treatment."
From the overall view of potential water supply shortages in the
United States, advanced waste treatment has the greatest promise at
locations where the municipal wastewater is presently discharged into
38
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the ocean or other sink and is thus lost for reuse. These locations
include some of the largest American cities, such as New York, Los
Angeles and San Francisco, where population concentrations are high,
and where it is becoming increasingly costly to follow the conventional
approach of reaching out into more remote interior locations to import
additional water supplies. This also includes the arid and semi-arid
regions where treated effluents have not been reused.
One of the largest alternative sources of water available to a city is
the wastewater which it has thus far thrown away. As a rule of thumb,
some 60% to 90% of the water delivered to a city is returned to waste
discharge. If treated to the conventional secondary level, this
water contains usually less than 0.1% of impurities, and advanced
waste treatment can further serve to make it completely suitable for
a wide range of reuses.
The United States learned a lesson in this regard during the severe
drought of 1965 in the Northeastern Region. New York City was particularly
hard hit; air conditioning was shut off; businesses shut down or lost
customers; restaurants could serve a glass of water only upon request.
Yet 3 billion gallons of unused water were flowing down the Hudson
River into the ocean each day -- about three times the amount consumed
daily by the City. The water was unusable because it was polluted.
Emergency conservation measures were instituted immediately to relieve
the most pressing hardships. Studies were started to consider the
alternatives available to secure additional fresh water supplies to
prevent a recurrence of water shortages in the future. Sea water
desalting and waste water purification were the two most important
alternatives to importation from the interior watershed.
Not surprisingly, desalting came out second best to advanced waste
treatment. A feasibility analysis of a 100 million gallons per day
advanced waste treatment plant which could be added to an existing
secondary sewage treatment plant showed that the plant could be
constructed for $33 million (at then-prevailing prices and interest
rates) and would produce and deliver potable water into the City's
system at about 16 cents per 1,000 gallons. The costs for the desalting
alternative were considerably higher. It is likely that this desalting
cost disadvantage will continue in most locations, if only for the
simple reason that sea water contains some 3.57, of dissolved salts
plus some organic matter -- equivalent to more tihan 35 times as much
foreign matter as secondary sewage effluent.
The advanced waste treatment facility postulated for the New York City
situation envisioned the following steps:
A. A second stage, intensive biological treatment process would be
installed following the existing high rate activated sludge treatment.
This second stage bio-oxidation would provide more than 90%
39
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removal of all biochemically oxygen-demanding (BOD) organic
compounds entering the treatment plant. In addition, the 3.5-hour
additional aeration would eliminate essentially all of the ammonia
and organic nitrogen from the waste stream.
B. The effluent from the biological treatment process would be
subjected to a coagulation-sedimentation and sand filtration
sequence similar to that utilized in conventional water treatment
plants. These purification procedures are capable of removing
both suspended and colloidal particles to produce a sparkling
clear water. The alum coagulation also serves to reduce bacterial
and viral disease-producing organisms.
C. From the filters, the water would pass through deep beds of
granular activated carbon which will adsorb residual dissolved
organic impurities from the water.
D. While this series of purification steps will yield a high quality
water, a final positive disinfection step, complete with fail-safe
provisions and a very large factor of safety, would be imposed.
The disinfection step would employ three separate chlorination
contactors; while one is being filled and another emptied, the
third will provide an absolutely certain contact with free chlorine
This batch or fill-and-draw system would eliminate even a remote
possibility of inadequate contact time for bacterial and viral
control.
E. Quality of the product water would be continuously monitored
and, in fact, the entire plant would be highly instrumented both
for control and for quality monitoring purposes to assure the
complete safety and reliability of the operation.
F. The product water would be pumped through a 1000-ft. force main
to an existing but presently unused shaft, extending downward
directly to the city's principal water distribution tunnel to
Brooklyn and Queens, and injected into the tunnel at a pressure
of 150 psi. The tunnel now carries 400 to 600 million gallons
of tap water each day which would provide a dilution factor of
at least 3:1 for the renovated water. The combined supply would
be completely potable in every respect and should meet or exceed
the highest Public Health Service Drinking Water Standards.
The treatment process proposed for New York City is only one of many
alternative systems available. The final system selected depends on
the use of the water and the impurity to be removed.
In returning to the broader effort in the United States to research,
develop, and demonstrate new technology for sewage treatment, this
discussion will attempt to categorize the effort in general terms
first, and then proceed to the specifics. Basically, our most urgent
needs fall into two broad categories:
40
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(1) We need treatment processes for more effective removal of organics,
nutrients, and suspended solids, which are now only partially removed
by "conventional" treatment; and
(2) We need processes for the removal of dissolved pollutants not
ordinarily removed at all by "conventional" treatment. Within and
across these two broad categories, two lines of attack are being
pursued:
(1) Modifications of "Conventional" Processes; and
(2) "Advanced" or Tertiary Processes
Now to the specific efforts underway:
I. MODIFICATION OF CONVENTIONAL PROCESSES
In this category some eight projects are now in the design or
construction stages, and three projects are already in operation.
A. Modification of the Activated Sludge Process for Increased
Nutrient Removal
At Manassas, Virginia, and at three locations in California
(Santee, Irvine, and Chino), these study efforts are underway:
1. Nutrient removal through biological oxidation; involving
very high organic loadings in the aerators and rapid
solids-liquid separation.
2. Progressive bio-oxidation; aerobic oxidation of nitrogen
compounds to nitrates, followed by anaerobic conversion
of nitrates to nitrogen gas.
3. Three-stage nitrification-denitrification; high-rate
activated sludge process, treatment with sludge enriched
with nitrifying bacteria, denitrification with anaerobic
bacteria.
B. Combined Trickling Filter - Activated Sludge Process
At Dallas, Texas, and Ventura, California, projects are underway
to evaluate tandem use of both processes in different sequences
to determine how trickling filters must be supplemented by
additional treatment to produce satisfactory effluent.
C. Dual-Train Experimental Activated Sludge Plant
At Washington, D. C.; one train to furnish effluent to tertiary
processes, the second to study modified activated sludge
processes. (Operates in conjunction with existing tertiary
pilot plant.)
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D. Polymer Addition to Activated Sludge Process for Phosphorus
Removal
At Washington, D. C.; an operational project involving addition
of three polymeric materials to raw sewage to increase sedimentation
of solids in primary settling tanks. Evaluation of effects
of this treatment throughout plant, including the anaerobic
digesters.
E. Mineral Addition to Activated Sludge Process for Phosphorus
Removal
At Pomona, Santee and Irvine, California; lime precipitation and
ammonia stripping for treatment of digester supernatant; addition
of sodium aluminate to aerator; single-stage tertiary clarification
and filtration using lime or alum as coagulant; Dorr-Oliver
process involving chemical and biological methods for phosphate
removal from raw wastewater, with lime recovery and reuse.
II. TERTIARY PROCESSES
Some ten tertiary treatment research and demonstration projects
are operational in various parts of the United States, and another
nine are in the design or construction stage. The areas under
investigation include the following:
A. Chemical Coagulation, Sedimentation, Filtration, and Granular
Carbon Adsorption - Emphasis on tertiary processes to reduce
suspended nutrients and organics because they contribute so
heavily to the overall water pollution problem.
B. Direct Carbon Treatment of Secondary Effluent - For removal of
organics from clarified secondary effluents.
C. Ammonia Stripping - Countercurrent air contacting lime-clarified
secondary effluents containing nitrogen as ammonia as organic
forms.
D. Electrodialysis - Lime coagulation and granular adsorption
precedes effluent passage through electrodialysis stack; 40%
of dissolved salts removed with a wastestream only 10% of
feedstream.
E. Ion Exchange - Parallel operation of electrodialysis unit for
comparison of process economics.
F. Reverse Osmosis - Different membrane configurations tested on
same wastewater to achieve higher flux rates and product-to-
waste ratios, with critical determination of pretreatment
techniques necessary to prevent fouling and deterioration of
membranes.
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Summary of Research Progress Achieved to Date
A wide range of wastewater treatment processes have been evaluated from
laboratory-scale through pilot-scale in recent years. The treatment
methods investigated include processes for suspended solids, organic
and inorganic removal, nutrient removal, and, conjuctively, certain
aspects of the biological processes. A number of processes have been
studied extensively enough to assess their feasibility with a fair
amount of accuracy.
For wastewaters with appropriate mineral composition, lime clarification
will effectively remove suspended solids and the nutrient phosphate.
Alum clarification is expected to be successful at a cost of 8 cents/1,000
gallons at the 10-mgd plant. For organics removal, activated-carbon
treatment is promising. Granular carbon treatment without clarification
of the feed can be carried out for about 8 cents/1,000 gallons or
less at the 10-mgd level on high quality secondary effluent. Powdered
carbon treatment has been estimated to cost about 12 cents/1,000 gallons
at the same plant capacity, provided the carbon can be reactivated;
this treatment yields a highly clarified water. For removal of gross
inorganic content, electrodialysis treatment should be possible for
about 16 cents/1,000 gallons or less in a 10-mgd plant, although pre-
treatment appears to be a necessity. Ion exchange will cost about
25 cents under the same conditions. Reverse o smosis has great promise
for effective results. It is still in a developmental stage and costs
are difficult to estimate. Removal of nitrogen, either as ammonia or
nitrate, is a difficult problem. An air-stripping process for ammonia
may be technically feasible at 3 cents/1,000 gallons or less for a 10-mgd
plant, but requires lime clarification to adjust pH to 11 or above.
Studies of denitrification of a highly nitrified effluent on granular
stone or sand shows promise for nitrate removal at 3 cents/1,000 gallons
for a 10-mgd plant. Electrochemical treatment appears at present to
be economically unfavorable.
The Outlook
In summary, a great deal of research progress has been made, and the
outlook for the future is bright. A range of processes have been
evaluated and improved to the point where the designers of new systems
have a great range of technological options in selecting efficient
treatment processes for various wastewater streams and effluent
qualities. We must depend on current and future studies, however, to
provide the optimum process selection.
As in the past, the economics of particular processes and combinations
will greatly influence the design and selection of individual systems.
The costs set forth in the table below apply to a 10-mgd plant and
include amortized construction, operation and maintenance costs; they
are projected best estimates for the tertiary processes shown, and
are based on actual experience for the conventional primary and
secondary treatment stages.
-------
Process Cost
(cents/1,000 gallons)
Conventional
Primary treatment 7.5
Activated sludge 11
Filtration
Microscreening 1-5
Coarse Media 2.5
Fine Media 3.5
Phosphate Removal
Mineral Addition to Aerator 3
Coagulation, Sedimentation (lime ovalum) 7
Coagulation, Sedimentation, Filtration 10
Ammonia Stripping 3
Granular Carbon Adsorption 4-8
Dissolved Inorganic Removal
Electrodialysis 14
Reverse Osmosis 25
Ion Exchange 25
In summary, advanced treatment for the removal of nutrients, organics,
and inorganics can be accomplished for about 26-30 cents/1,000 gallons
compared to 11 cents/1,000 gallons for secondary treatment. However,
the wastewater reclaimed by the improved or advanced treatment has
economic utility and value as related to the reuse application selected
for it, and, by logical extension, becomes once again available for
sale, to the user.
As a final word about economies of scale for the electrodialysis and
reverse osmosis dissolved inorganic removal processes, pre-publication
results of current work by Interior's Office of Saline Water indicates
that a 30-mgd plant located in a Southern California could demineralize
secondary effluent at 21 cents/1,000 gallons for the electrodialysis
process, and at 22 cents for the reverse osmosis process, both at 1968
prices .
44
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SALINITY CONTROL IN RETURN FLOW
FROM IRRIGATED AREAS
A DEMONSTRATION PROJECT
by
Norman A. Evans I/
The Upper Colorado River Basin comprises approximately 220,000 square
miles in the states of Utah, Colorado, New Mexico, Arizona and Wyoming.
The main stem of the Colorado River heads in Colorado at the Continental
Divide and runs more than 500 miles southwestward through Utah and
Arizona to a place called Lees Ferry, which marks the division between
the Upper Colorado River Basin and the Lower Colorado River Basin. This
river and its tributaries literally is the lifeline of southwestern
United States.
Although problems abound in the utilization of the water, none is
considered so great as the mineral degradation which occurs as the
water flows westward. This problem is serious because the basin is
approaching conditions of full development and utilization of the
available water supply.
The seriousness of mineral pollution in the Colorado River is illustrated
by the 1963 salinity crisis at the U. S.-Mexico border arising from
saline drainage from the Welton-Mohawk irrigation project. Here,
as a solution, the federal government provided a waste canal to carry
the return flow from the project around Imperial Dam. Such drastic
measures cannot be expected to be used to solve other salinity problems
along the river. Methods and practices must be developed which will
afford control of the salt load in the river while permitting continued
use of the water.
Salts in the river accumulate from several sources but the heaviest
contributor is water returning to the river from underground drainage
after it has been used for irrigation on lands near the river.
Figure 1 represents a typical geologic cross section along the upper
Colorado River. Note the shale base material over which has been
deposited alluvial material which now constitutes the irrigated soil.
This figure also shows a water budget, indicating water applied as
irrigation on the land, seepage losses from the canal, deep percolation
into the ground water of a fraction of the irrigation water applied,
and evapotranspiration into the atmosphere of a part of the irrigation
water applied. Lastly, a component of the irrigation water applied
is shown running back to the river as surface runoff.
I/ Director, Natural Resources Center, Colorado State University,
Fort Collins.
-------
FIGURE I - TYPICAL GEOLOGIC CROSS SECTION
-------
Water returned to the atmosphere by evapotranspiration leaves behind
in the soil any salt which it contained when it was applied to the land.
That salt residue left behind may be dissolved by deep percolation
water and carried back to the river. This is one source of salt load
returning to a river and in some cases, especially where the irrigation
water contains a heavy load of salt, can contribute a large salt load.
Seepage from a canal passing through the soil as it moves toward the
river may also dissolve salts from crystalline form in the soil and
thereby gain a load of salt. These two processes by which salt is
added to return flow might be called (1) evapotranspiration residue,
and (2) solution pickup.
In the Upper Colorado River the irrigation water has relatively low
salt load, on the order of 300 ppm, so the evapotranspiration residue
is relatively small. On the other hand, solution pickup is relatively
high because the parent material and base material contains large
amounts of crystalline salt. Figure 2 shows electrical conductivity
(ECX1CH) and exchangeable sodium percentage (ESP) in soils and shale
of Grand Valley.
Figure 3 is the Upper Colorado River Basin showing the main stem and
principal tributaries. The numbers show the annual salt load at three
points expressed in tons. At Cameo, Colorado, the annual salt load
is 1,549 tons. At Cisco, Utah, the annual salt load is 4,242 tons.
The Gunnison River at Grand Junction adds 1,519 tons. Quick arithmetic
shows that the salt load gain in this section of the main stem of the
Colorado River is 1,174 tons. This is almost equal to the load at
Cameo and is primarily the result of solution pickup in return flow
from irrigated land along the river.
The purpose of this paper is to summarize a demonstration project which
has been initiated in the Grand Valley area (Figure 3) for the purpose
of showing that saline agricultural return flows are controllable and
that if improvements in water management practices are applied, the
salt load returning to the river will be reduced.
Mechanics of Return Flow
Before describing the demonstration project, a brief discussion of the
nature of return flow will be helpful. Figure 4 represents a typical
irrigated area along the river. Phreatophytes are illustrated because
the water-loving plants are almost invariably found along western rivers
Now let us look at the hydrograph of return flow as computed from a
2-dimensional mathematical model. Figure 5 shows the return flow
during and after the irrigation season. Note that the return flow
is negative at first. The water table at time zero is assumed hori-
zontal and the negative return flow represents phreatophyte withdrawal
of water from the river. However, as the groundwater rises, flow
returns to the river reaching a peak shortly after the irrigation
season ends and gradually declining thereafter. Let's look now at the
47
-------
oo
25
20
ro
O
x
o 15
UJ
CL
(ft
UJ
10
0
12
ESP
EC x I01
12
22
16
26
18
0-9 9-18 18-30
DEPTH IM INCHES
FIGURE 2 - SALT STATUS OF SOILS AND SHALE
30-48
70
RAW SHALE
-------
FIGURE 3 - UPPER COLORADO RIVER BASIN
49
-------
NN NN N N N NN N NNNNNNN X N NNNNNNN N N. X N N NNNNNN
VALLEY BOUNDARY
CANAL
IRRIGATED LAND
PHREATOPHYTES
RIVER
FIGURE 4- IDEALIZED IRRIGATED AREA
-------
IRRIGATION
CANAL SEEPAGE, PHREATOPHYTES
ALONG RIVER, OVER-IRRIGATION
CANAL LINED, PHREATOPHYTES
REDUCED 50%, OVER IRRIGATION
REDUCED 50%
180
DAYS AFTER IRRIGATION
360
FIGURE 5 -HYDROGRAPHS OF RETURN FLOW
-------
effect of improved water management by eliminating canal seepage,
reducing the area of phreatophytes by 50 percent, and reducing the
amount of deep percolation by 50 percent. By eliminating canal
seepage, we notice first that the peak runoff is smaller and occurs
earlier. Comparing the areas under the two curves indicates a reduced
total volume of return flow. It has been frequently observed that
salt load in return flow is proportional to volume of water returned,
so we might expect a reduced total amount of salt to enter the river.
The mathematical model has been used also to illustrate the effect
of system geometry on return flow. Figure 6 shows a river valley with
the main canal located one-fourth the distance from the river to the
valley boundary. Canal seepage is considered for a given period of
time and the resulting hydrograph of return flow is displayed. Note
that it has a high peak rate of return dropping off rapidly. The second
case locates the canal at the valley boundary. This is generally more
typical of the Colorado River Valley. The same amount of seepage
during the same time is reduced and the return flow hydrograph is seen
to be much flatter and with the peak occurring much later. Of course
both situations return the same volume of water to the river but with
a different rate distribution. Unfortunately, we know very little
about the effect of return flow rate on solution pickup.
Demonstration Project
A demonstration project to show effects of seepage reduction on salt
load was proposed by the principal water-using identities in the Grand
Valley near Grand Junction, Colorado. Six irrigation companies, a
power company, and a drainage district combined resources to form a
corporation for the purpose of conducting the demonstration and study.
They received a grant from the Federal Water Pollution Control Admin-
istration for construction and project evaluation. A contract was in
turn negotiated by the corporation with Colorado State University for
assistance in evaluating the results of the project. The study area
is represented in Figure 7.
The first step in the evaluation program was a "before treatment"
inventory of water and salt budget in the demonstration area. Canal
seepage losses have been measured and a plan for lining certain sections
of canals is being formulated. This lining will be constructed during
the forthcoming winter season prior to the 1970 irrigation season.
An "after treatment" inventory will be made during and after the 1970
season.
Water Budget
Water flow measurement in all canals, ditches, and drains leading
into and out of the study area are being made using a wide variety of
measuring methods. Measuring flumes have been used in some places,
existing structures have been calibrated for measurement in others,
and dye-dilution has been used for measurement where other methods
52
-------
CONSTANT CANAL SEEPAGE
BOUNDARY
CANAL
Ul
CO
UJ
t-
tr
o
_i
U-
z
tr
LU
cr
IRRIGATED AREA
30
60
90
ISO
DAYS
360
FIGURE 6—INFLUENCE OF CANAL LOCATION ON RETURN FLOW
-------
o
c
;o
m
;o
m
i ..Government //
f~" *~~-.,------^
^
— *•
\ \
\ \
\
\
1
-------
were not possible. Evapotranspiration estimates will be made from a
survey of vegetation type and density. The estimate will be made
by the Jensen-Haise method of calculation.
Groundwater flow will be calculated from hydraulic gradient and per-
meability data. A grid of piezemeter installations has been made
with which the groundwater flow net can be measured. Permeability
measurements in situ by standard methods will also be made. River
flow measurements upstream and downstream from the demonstration area
also will be made.
Salt Budget
Salt monitoring the river will afford the final evidence of positive
benefit from reduction in canal seepage. However, the lag time in
return flow for this particular system is uncertain so salt monitoring
in the groundwater will also be performed. A grid network of porous
cups has been installed in the alluvium at several depths from which
groundwater samples will be extracted. Changes in sale flux at these
sampling points will add evidence as to the effect of reduced volume
of groundwater flow.
Summary
Water users in the Grand Valley area of Colorado have long recognized
the damaging effects of canal seepage and excess water application in
irrigation. They have seen it in the progressive deterioration of
agricultural land beginning shortly after irrigation was introduced
to the area. They also recognized river quality deterioration which
has been outlined in these remarks. With the cooperation and assistance
of the Colorado Water Conservation Board and the strong interest of
the Federal Water Pollution Control Administration, these citizens
set about doing something about it through a demonstration project
financed by FWPCA. Canal seepage will be reduced. This should reduce
by 1/2 the volume of return flow, and affect a significant reduction
in salt load originating from solution pickup. We believe also the
attention focused upon water management through this demonstration
will result also in greater effort toward better irrigation water
management on farms which in turn will further reduce return flow
vo1ume.
While return flow control will reduce salt load, a certain amount is
essential for maintenance of salt balance and we do not suggest that
elimination of all return flow is an objective - rather its control
to satisfy salt balance requirements.
It is expected that the experience gained in this project will serve
as a guide to other similar areas along the entire Colorado River as
well as other areas of the western United States.
55
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WATER QUALITY CONTROL PROBLEMS IN INLAND SINKS
by
Richard C. Bain, Jr. and John T. Marlar !/
INTRODUCTION
All rivers do not flow to the oceanic sea; some create their own
unique inland seas in the desert. Desert lakes like desert lands
are harsh, and few life forms survive. The tenuous balance between
vegetative cover and precipitation, animal life and water supplies
in arid lands is reenacted with different players in the desert lake.
Here survivors from a wetter past or newcomers introduced by man,
struggle in the specialized environment created by rivers without
outlets.
The arid lands of the western United States contain numerous closed
river basins, or inland sinks, which have unique water quality and
ecological problems. Each of these basins will support an inland
sea which typically is increasing in salinity, has fluctuating water
levels and various ecological problems associated with salt, nutrients
or pesticides often from agricultural drainage. Since these sumps
are rarely or never flushed, the trend is toward ecological imbalance
as a result of salt buildup.
Figure 1 is a comparison of recent salinities in six well-known inland
sinks in the Western United States. These inland seas are in various
Stages of "aging" as far as water quality is concerned. Several of
these seas are becoming more saline at a rate faster than nature alone
would dictate, because the freshwater inputs have been reduced or made
more saline by man. Pyramid Lake in western Nevada is a good case
study illustrating the effect of inflow reductions on the aging process,
The Salton Sea, in southern California receives relatively saline
inflows comprised of drainage from irrigated lands. The water quality
and quality related problems affecting aquatic life resources of
these rather different desert lakes will be described to emphasize
the unique water quality management problems which occur in inland
s inks.
PYRAMID LAKE
Background
Pyramid Lake is the largest remaining remanant of ancient Lake
Lahontan. Its present area of 100,000 acres is only one-fiftieth
that of its Pleistocene ancestor. Pyramid Lake has been appropriately
I/ Respectively, Chief, Operations Branch and Sanitary Engineer,
Planning Branch, California/Nevada Basins, Federal Water Pollution
Control Administration, USDI, 620 Central Avenue, Alameda, California.
57
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270,000
o>
E
V)
o
60,000
50,000
40,000
30,000
20,000
10,000
I
*
I
v»
»
^
1
•*
FIGURE I - SALINITY OF SIX INLAND SINKS
58
-------
called North America's most beautiful desert lake. Set at an altitude
of 3,800 feet in the practically barren Nevada desert, it is indeed
a rewarding sight to view its vast expanse of blue-green waters
ringed by peaks of brown. It is a welcome relief from the surrounding
arid lands.
The life blood of any lake is its water source. The Truckee River
which originates in Lake Tahoe and flows past Reno, Nevada, has been
the major source of water to Pyramid Lake (Figure 2). The River
apparently supplied sufficient water to the Lake to result in a
reasonably constant surface elevation in Pyramid Lake until 1910 when
Xruckee River water was diverted at Derby Dam, the first reclamation
project undertaken in the West by the U. S. Reclamation Service, now
the U. S. Bureau of Reclamation. Truckee River water is diverted
to the Carson River Basin where it is stored in Lake Lahontan for use
by the Truckee-Carson Irrigation District. Drainage from the District
flows to the Stillwater Wildlife Refuge in the Carson Sink. Although
there are some additional diversions from the Truckee River upstream,
the diversion at Derby Dam has been the most important single factor
affecting Pyramid Lake in this century.
Prior to 1910 the entire flow of the Truckee River was tributary to
Pyramid and Winnemucca Lakes. Based upon data and analyses assembled
by Harding (1) the total flow reaching the two lakes during the period
1780-1905 averaged 546,000 AF/Yr. After major diversions for irrigation
purposes began in this century, Lake Winnemucca received no overflows
from Pyramid Lake and finally evaporated to dryness in 1939. Recent
discharge of the lower Truckee River tributary to Pyramid Lake (1957-67)
has averaged only 223,000 AF/Yr. (2).
When the diversion of Truckee River water through the Truckee Diversion
Canal started, Pyramid Lake held over 35 million acre-feet and had
a surface area estimated at over 120,000 acres. Since that time, due
to the unbalanced water budget, the Lake has increased in salinity
by about 50 percent, receded some 80 feet in depth, lost 15 million
acre-feet in volume, and 20,000 surface acres. Figure 3 shows salinity
trends based on several data sources (1,3,4). During the 1940"s
the famous Lahontan Cutthroat trout disappeared from the Lake. It
was erroneously concluded by biologists at that time, that the increase
in dissolved solids had become toxic to the trout. However, in 1948,
experiments demonstrated that trout could survive lengthy exposure
to Pyramid Lake water. The lowering of the Lake surface had caused
an increase in the gradient of the lower Truckee River and a shallow
delta formed at the River's entry to the Lake which blocked the access
of the trout to their spawning areas in the River. Thus streambed
changes caused by the lowering of the Lake had caused the population
of cutthroat trout to disappear. Restocking programs have since
been initiated by the Nevada Fish and Game Commission.
Although the ultimate tolerance of Lahontan Cutthroat trout to dissolved
solids has not been adequately defined, it is known that certain
59
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ON
O
WINNEMUCCA
<'LAKE ,'
V-PYRAMID LAKE
SAMPLING STATIONS
\ CARSON ,
\ SINK + '--'
Pyramid LOIM Indian R«s«rvo1ion
StillwoUr
Ar«o
DERBY
DIVERS/OKI DAM
WASHOE
LAKE
LAKE
TAHOE
CARSON LAKE
— IRRIGATION AREA
FIGURE 2- TRUCKEE -CARSON RIVER AREA
-------
I860
1880
I90C
1920
tr
<
ut
1940
I96(
3000
Derby Diversion Dam Completed
4000 5OOO
TDS (mg/l )
6000 7000
FIGURE 3 - HISTORIC TREND OF TOTAL DISSOLVED
SOLIDS -- PYRAMID LAKE
61
-------
physiological changes may occur with continued exposure to IDS levels
above 10,000 mg/1. Trout transplanted to Eight Mile Lake, Wyoming,
exhibited evidence of liver anomalies after two or three years in
12,000 to 13,000 mg/1 TDS lake waters (5). Even though the fish were
said to be of "good sporting quality" no assurance was given that the
trout population could be maintained indefinitely at IDS concentration
of 13,000 mg/1. These experiences should serve as advance warnings
of the probable future effects of the imbalanced water budget of
Pyramid Lake.
Other fishes of interest include the Cui-ui sucker (Chasmistes cujus)
which is believed to occur only in Pyramid Lake. This species has
adapted to the changed hydrologic regime and presently spawns in the
gravels around the shore of the Lake. The Cui-ui is included on the
Bureau of Sport Fisheries and Wildlife list of endangered species.
The apparent effects on the biota and desired use of the Lake have
thus far been intimately connected with the physical changes caused
by man rather than from the chemical or biological changes resulting
from his actions. The effect of physical changes which prohibited
the spawning run of the Lahontan Trout is not the only problem caused
by lowered lake levels. A $500,000 park being planned for Pyramid
Lake has also been affected because boat launching facilities and
restroom facilities will eventually have to be moved once the Lake
level has receded from them.
Pyramid Lake Water Quality
Chemical and biological changes may be more subtle. A brief water
quality survey by FWPCA in the fall of 1968 was performed in order to
document the present state of water quality in Pyramid Lake and provide
base data from which to estimate probable future conditions. These
are the only known detailed data on the hypolimnion of the Lake.
Although the sampling was performed after the fall overturn had started,
it is apparent that a stable stratified condition still existed.
The bottom of the epilimnion was noted at about 70 feet, while the
summer depth has been recorded at 20 to 25 feet (3).
Dissolved oxygen, temperature, and salinity profiles for two stations
within the Lake are shown in Figure 4. These profiles demonstrate
the effect of thermal stratification within the lake; organic matter
which falls from the epilimnion decomposes in the deeper waters and
produces the characteristic oxygen depression found in many lakes.
The stratification of dissolved solids as indicated by the conductivity
measurements is indicative of the large evaporative loss experienced
by the Lake during the stratified period and the lack of exchange
between the upper and lower portions of the Lake during stratification.
The mean TDS was 5420 mg/1 consisting principally of sodium, chloride
and bicarbonates. TDS levels were below 3500 mg/1 in 1882 and below
4000 in 1933.
62
-------
DO(mg/l )
5 10
(TEMP C°)
10 ^ 15
50-
i r
i
i
*
i
i
i
i
Conductivity ^^j
.s"^ x/
\
^r~*
o
f
J^~ Temp
X ' I v
/ / /
8500
DO Probe
Trace
Winkler
Values
STATION No. 3
Off Sutcliffe
Oct. 1968
15 0
2O 5
DO (mg/l)
5 10
(TEMP C° )
10 _ 15
15
20
STATION No. 4
Off Truckee River
Oct. 1968
8700 8900 9100 85OO 8700
CONDUCTIVITY
8900
9100
FIGURE 4 - DEPTH PROFILES OF TEMPERATURE CONDUCTIVITY
8 OXYGEN
PYRAMID LAKE
63
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The concentration of the nutrients, nitrogen and phosphorus from the
1968 survey is fairly high. Total nitrogen averaged 0.58 mg/1 and
total phosphates (as P) averaged 0.12 mg/1. Although algal blooms
have been reported to occur with regularity in the Lake, there have
been no reports of conditions resulting in fish kills or other oven
signs of extreme eutrophy. It is suggested that these are yet to
come. In 1962, La Rivers described the Lake as "literally a culture
medium for all organisms in the food chain—temperatures are warm,
nutrients plentiful and fish growth rapid" (6). With the combination
of present agriculture and the rapidly growing urban area around
Reno and Sparks, Nevada, contributing nutrients in return waters
and sewage to the Truckee River complexed with the effects of evaporation,
it is certain that the future water quality of Pyramid Lake will suffer.
The Future of Pyramid Lake
Preliminary estimates indicate that continuation of existing water
use practices together with projected nutrient inflows will cause the
present nutrient levels to nearly triple in the next fifty years.
Algal growth is expected to increase as a result of increased nutrient
loadings. Increased primary productivity in Pyramid Lake is expected
to supply enough biodegradable organic material to result in anoxic
conditions in the hypolimnion of the Lake within the coming fifty-
year period. Limnological investigations should be carried out to
monitor the Lake algae, nutrient and oxygen levels. Control of nutrient
discharge to the Truckee River may be necessary to arrest the rate
of eutrophication of Pyramid Lake. Controls might include tertiary
treatment, land disposal, or diversion of effluents to the Truckee-
Carson Irrigation District.
From the time Pyramid Lake was deprived of an outlet, it was destined
to eutrophy and became more saline at a faster rate since it is now
the repository of all nutrients and other salts which are washed in
with the tributary flow. Accepting this premise, water quality control
becomes focused on means to reduce the rate at which such terminal
water bodies are allowed to deteriorate.
Efforts have been made recently by the Department of the Interior to
maximize flow available to Pyramid Lake while satisfying other
existing water rights. A 1964 Task Force Report (7) to the Secretary
of the Interior resulted in the formation of the Interior Committee
on Operating Criteria and Procedures--Truckee and Carson River Basins.
Due to the efforts of the Interior Committee, the coordinated operations
of the Truckee and Carson Rivers have been controlled by operating rules
and regulations instituted on October 1, 1967. Additional water
reaching Pyramid Lake during the first year following use of the
operating rules has been estimated at between 73,000 and 125,000 AF.
The operating rules and regulations are set annually to provide the
flexibility to make needed changes and adjustments which would result
in better use of the water resources available. Even though the current
64
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water year (1968-69) is much above normal, an additional 40,000 to
60,000 AF has reached the Lake due to basin operation under the Interior
Committee operating rules this year. Thus, it is apparent that con-
siderable progress has already been made in arresting the decline of
the Lake. The Committee is optimistic that even though the water
budget for the Lake has not been balanced, further progress can be made.
In its efforts to provide a solution, the Interior Committee has
considered other approaches to the problem. These include the possi-
bility of reducing the evaporative loss by artificially mixing the
Lake or by the use of monomolecular films. Preliminary studies indicate
neither evaporation suppression approach appears feasible; mixing
indicates a theoretical water savings during summer months but heat
storage is expected to increase winter evaporative losses; film methods
may be prohibited by the high winds on this high desert lake. Studies
by the Interior Committee are continuing toward the development of a
long-range water management policy for the Truckee and Carson Rivers
and Pyramid Lake.
SALTON SEA
Background
The Salton Sea is an inland sink in a low-lying desert area south and
east of Los Angeles, California (Figure 5). The 230,000-acre sea
is threatened with rapidly rising salinity levels which, if uncontrolled,
are expected to eliminate the currently valuable sport fishery within
the next decade. The Sea has a volume of 6.0 million acre feet at
its present water surface elevation of about 232 feet below mean sea
level. Fluctuating water levels and eutrophication symptoms such as
dissolved oxygen deficiencies in deeper waters, discolorations,
turbidity and odors caused by dense phytoplankton populations are
also major Salton Sea problems.
The Salton Sink Sea Basin, which in its lowest part is 278 feet below
sea level, was the site of a large lake in Pleistocene times called
Lake Cahuilla. Several geologic histories have been written on the
Sink and the theories conflict regarding a possible connection with the
Gulf of California. One possible explanation is that the 8360-square-
mile Salton Sea Basin was cut off from the Gulf as the Colorado River
extended its delta. During the last century water entered the Sink
from the Colorado River on several occassions forming a small sea
first discovered in 1850's. A 100,000-acre lake was formed in 1891
through a connection between the Alamo River and the Colorado River.
This water evaporated rapidly and was mined for salt the following year.
The "modern" Salton Sea was formed by floods in 1905-07 which cut
through a channel which carried irrigation water from the Colorado
River to the Imperial Valley. The break in the channel was repaired
by 1907 and since that time the Sea inflow has been controlled by
65
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-SAMPLING STATIONS
12
NOTE;
^m * J 1 "
MILES
Water surface elevation of the Sea as
shown Is 235 feet below mean sea
level.
WESTMORLAND \ \
BRAWLEY ji
• WEST
( »ALAMORIO
FIGURE 5 - SALTON SEA STUDY AREA AND SAMPLING STATIONS
66
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irrigation practice. The salinity of the Sea has increased from less
than 4,000 mg/1 in 1907 to about 37,000 at the present time. Salinity
levels approaching ocean values have persisted for nearly 50 years while
water levels were rising. Slightly higher salinities, up to 40,000
mg/1, were observed during the late 1940*s due to reduced inflow.
Salinity is increasing in the Sea now that water levels are more
stabilized. See Figure 6 for historical salinity observations.
Published data are available on chemistry of Salton Sea waters, including
a review of ionic composition from 1907 to 1955 included in the Cali-
fornia Fish and Game Bulletin edited by Walker (8) and of 1964 sampling
efforts described by Pomeroy (9). Recent data show salt levels are
approximately equal to oceanic salinity although ionic composition is
somewhat different. Salton Sea sulfates are approximately triple,
calcium about double and chlorides 20 percent lower than typical
ocean water values. Oceanic fish, barnacles, and algal species are
now common in the Salton Sea.
Most of the drainage to the Salton Sea comes originally from the
Colorado River near Yuma, Arizona, where waters containing about 850 mg/1
salt are diverted through a series of canals westward to the Imperial
Valley and Coachella Valley for irrigation use. Drainage from irrigated
land collected in open field drains and subsurface tile drains is
channeled to the Salton Sea. Evaporation, transpiration, and vegetative
uptake of water applied to the land concentrate the salts in the moisture
remaining in the field soils. The resulting drainage is often 3 to
5 times as saline as the irrigation supply and may be much higher if
excess salts have accumulated in the soil. The character of this
drainage usually is of a sodium-chloride-sulfate character in contrast
to the sodium-calcium-sulfate supply. Of the annual 5 million acre
feet imported from the Colorado River for use in the Imperial and
Coachella Valleys and in Mexico about 1.2 million acre feet is returned
to the Salton Sea. Evaporation losses within the Salton Sea approximate
this annual inflow. Thus a hydrodynamic balance exists.
The Salton Sea currently supports a valuable sport fishery including
Corvina, Sargo and Bairdiella (Croaker) which were introduced in 1948
from the Gulf of California. These oceanic species have thrived in
the Sea but are not expected to tolerate salinity levels above 40,000 mg/1
Physiology studies conducted by the California Department of Fish and
Game indicate survival of eggs and larvae is unlikely above that
salinity. Adults may be more tolerant. Food chain organisms, of
which there are very few species in the Sea, are not expected to
tolerate any substantial salinity rise. The Sea is expected to pass
the 40,000 mg/1 level during the 1970"s unless a water quality
control plan is implemented. Delays will only increase the magnitude
of the control developments and their cost since salt buildup, currently
estimated at 5.6 million tons per year, is proceeding at such a rapid
rate in the Sea.
67
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UJ
UJ
UJ
cr
o
u.
o
to
z
o
oc.
UJ
u.
o
UJ
a?
o
18-r 300
16-
14-
12-
10-
8-
6-
4-
2 •
O-1- 0
YEAR
FIGURE 6 - SALINITY MINERAL CONTENT 8 VOLUME OF
THE SALTON SEA
68
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Water surface elevations have been generally rising in the Salton
Sea basin in contrast to the falling levels described in Pyramid Lake.
Rising water levels have flooded out shoreside developments and forced
bulkheading and channelization projects in other areas threatened
with flooding. The low angle of repose of the Sea bottom magnifies
the water level problems. Drainage waters flooded the federal wildlife
refuge during the 1930's, and today this area is primarily managed
as a waterfowl resting area.
The Salton Sea is objectionably eutrophic and is characterized by an
overabundance of mineral nutrients, mainly compounds of nitrogen and
phosphorus, which produce intensive "blooms" of floating, microscopic
plants (phytoplankton) in the upper levels of the water mass. Wind,
wave action and currents distribute these planktonic algae throughout
the Sea. The immediate visible results are discoloration and reduction
of clarity of the water. In addition, although phytoplankton are
essential to the ecological system of the Salton Sea, death and
decomposition of large populations of these algae often result in
temporary anoxic conditions, particularly in the deeper waters, and
subsequent production of obnoxious odors over extensive areas of the
Sea. Temporary anoxic conditions often occur in Salton Sea during
the summer months, commonly leading to fish kills and the disappearance
of other animals that are intermediate links in the biological food
chain of the Sea. Mats of decomposing benthic blue green algae which
are torn loose from the bottom occasionally form rafts of unsightly
and odoriferous scum on the surface of the Sea, particularly near shore.
Eutrophication symptoms such as these were described earlier by Walker
and co-workers as being prevalent in the years 1954, 1955, and 1956,
the period of their study of the Sea (8). These conditions have reduced
the aesthetic appeal of the Salton Sea and limited water contact
recreation such as swimming although fishing activity has probably
been stimulated by the productivity of the Sea.
The tributaries to the Sea carry high concentrations of nutrients
originating from agricultural drainage and sewage from the Imperial
Valley and from Mexico. The major tributaries averaged approximately
0.5 mg/1 total phosphorus and 7 mg/1 total nitrogen, primarily in the
nitrate form. See Table 1 for details on nutrient content of sources.
These sources discharge approximately 1 million pounds of phosphorus
and 25 million pounds of nitrogen annually to the Salton Sea.
Salton Sea Water Quality
Field measurements and water samples were collected on the Salton Sea
between July 1968 and May 1969. These data serve to document the
present quality of the Sea, its tributaries and the nature of any
water quality problems. Sampling stations are shown on Figure 5.
Samples and field data collected included nutrient samples at several
depths at each station, profiles of dissolved oxygen, pH, temperature
69
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TABLE 1
NUTRIENT CONCENTRATIONS IN SALTON SEA INFLOWS
Alamo R.
Org
NH3
NO 2
N03
0-P
T-P
•-N, mg/1
-N, mg/1
-N, mg/1
-N, mg/1
, mg/1
, mg/1
1
0
0
6
0
0
.23
.58
.32
.00*
.20
.29
New R.
0
0
0
4
0
0
.97
.47
.22
.48*
.29
.53
IID
Direct
0.
0.
0.
9.
0.
0.
40
15
04
98
04
06
White-
Water R.
0
0
0
6
0
0
.83
.16
.06
. 28*
.26
.53
Other
CV Drains
0
0
0
9
0
0
.40
.15
.04
.98
.04
.06
*Includes FWPCA and DWR data
observations of color, odor, transparency, light penetration profiles,
productivity measurements, chlorophyll and biological collections
including both plankton and benthic life. Extensive salinity data
were not collected since the mineral content of the Sea has been
documented; limited mineral data gathered confirmed that Sea salinity
has passed ocean values and is high in sulfate.
The mean total phosphorus and total nitrogen concentrations for the
Sea during the study period were 0.07 and 3.30 mg/1 respectively.
Seasonal data are tabulated in Table 2. A nutrient budget of the Sea
indicates that, on the average, about 45 million pounds of nitrogen
and one million pounds of phosphorus are present within the Sea waters.
Nitrogen forms within the Sea are predominantly organic in contrast
to the inorganically rich tributaries. Inorganic nutrients entering
the Sea are converted to organic matter through photosynthetic processes
Nutrient levels in Salton Sea bottom sediments also reflect the high
organic content of the sea waters. Sediment samples collected by
dredge and coring devices contained about 5 percent organic carbon,
0.3 percent organic nitrogen and 0.1 percent total phosphorus.
Data from field and laboratory studies of the Sea in 1968-69 also
provide further documentation as to the seriousness of fishery problems.
Extensive fish kills of species such as corvina and gulf croaker were
observed in the Sea near the Whitewater River inlet on two separate
occasions and dead mullet were seen near the Alamo River on one occasion,
Observations of dead fish were commonplace throughout the Sea.
Extremely unpleasant odors were also encountered; these were especially
70
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TABLE 2
SALTON SEA WATER QUALITY
N03-N (ing /I)
N02-N (mg/1)
NH3-N (mg/1)
Org.-N (mg/1)
Total N (mg/1)
Ortho P (mg/1)
Total P (mg/1)
pH (units) *
Temperature °C *
Transparency (feet)
Euphotic Depth (ft)
* Surface
Bottom
Summer
0.10
0.01
0.22
2.80
3.13
0.04
0.06
7.8
7.6
29.5
28.4
3.6
--
Autumn
0.16
0.06
0.36
2.90
3.48
0.02
0.05
7.6
7 .3
23.1
22.3
4.1
10.4
Winter
0.14
0.02
0.25
1.20
1.61
0.03
0.07
8.6
8.5
15.2
14.2
3.4
8.5
Spring
0.19
0.30
0.27
4.20
4.96
0.06
0.20
8.4
8.4
23.3
22.0
3.5
10.0
71
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prevalent near shore, often at the sites of marinas or popular fishing
grounds. Strong odors, especially the rotten eggs smell characteristic
of hydrogen sulfide (lUS) were often noted and were nearly overpowering
in the Whitewater River area at the time when one of the extensive
fish kills was observed. A level of H^S lethal to fish or other
animals could very well have been present in the water on that occasion.
High H2S levels were also reported in May 1969.
The density of algal populations in the Salton Sea at times was so
great that the water was highly discolored, varying in hue from a
brick red in some areas to brown and light green in others. Examination
of these water samples indicates that the brick red color was probably
due to dinoflagellates, brown by diatoms or fish eggs and green by
green flagellates. The Sea water was always somewhat colored and
always turbid. Secchi disc readings averaged about one meter varying
from about .5M to 2M; euphotic depths were approximately triple
Secchi disc values.
Dissolved oxygen (DO) concentrations in the euphotic zone _' were
invariably supersaturated during daylight hours, sometimes by a factor
of 200 percent reflecting trie incentive r^r.o .osyncr.e tic activity of the
massive phytoplankton population.
Dissolved oxygen measurements in the Sea at depths below the euphotic
zone (15 feet and below) for the months of July-November show that
the DO concentration often drops to dangerously low levels, at times
near zero. See Figure 7 for some representative profiles. Extensive
regions of the deep water during these months often contained less
than 3.5 mg/1 of oxygen during daylight hours. Lower concentrations
occurred at night when oxygen inputs from photosynthetic oxygenation
were absent. Water temperatures varied from 29.5°C in summer to
14.2°C in winter; pH levels ranged from 7.3 to 8.8, the highest values
being observed in surface waters during May.
Comparisons of organic production from other fertile waters show that
maximum levels of primary production are often similar in different
physical environments due to light limitations. Production of phyto-
plankton algae expressed as gms Carbon per square meter per day may
be the same in a 100-ft. deep euphotic zone in the ocean and in a
5-foot zone in an enriched murky bay made turbid by the phytoplankton
themselves. A plateau of maximum organic production is reached in
highly eutrophic waters as a result of this self-limiting effect.
This phenomenon is illustrated by Figure 8.
Odum has classified production rates for various ecosystems and shows
maximum values of 1.0 gram of carbon fixed per square meter per day
for oligotrophic (nutrient poor) lakes and oceanic areas (10).
2] The euphotic zone is often defined by the depth which sunlight
sufficient for photosynthesis occurs—of ten this is approximated by
the depth at which light energy equals 1 percent of surface light intensity,
72
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DO ( mg/I)
DO (mg/l)
t-
UJ
UJ
u.
Q.
UJ
Q
024 6 8 10 _ 12 0 2 4^6
10
15
20
25
30
35
0
5
10
15
Temp.
DO
10 12 14 16 18 20 22 16 18
DEEP STATION
WINTER
Temp
DO
10 12 14 16
18 20 22 16 18
SHALLOW STATION
20 22 24 26
SPRING
20 22 24 26
FIGURE 7 - DEPTH PROFILES OF TEMPERATURE ft OXYGEN
SALTON SEA
73
-------
UJ
a: o
S <°
O UJ
-5
O -1
UJ
z o:
o <
»- H
li
o a:
cr u
a a.
/—NATURAL EUTROPHICATION
AGE OF THE LAKE
Nott: Adapted from Hosier, A. O. Eutrophicotion of Lakes by Domestic
Drainage, Ecol ^8<4)I947
FIGURE 8 - PRODUCTION AND LAKE AGE --
SALTON SEA STUDY
-------
r\
Shallow, eutrophic lakes are expected to produce up to 5 gms C/m
day; values over 3 gms C/m^/day in aquatic systems are considered high.
Measurements of primary production in the Salton Sea during 1968
averaged about 3.0 gmC/m2/day and exceeded 5 gmC/m2/day, on several
occasions. These high productivity values are in the range expected
in the shallow, nutrient rich Salton Sea.
The Future of the Salton Sea
A salinity control plan is undergoing study by agencies of the Department
of Interior and the State of California. A reconnaisance Report, to
be published by the Bureau of Reclamation in 1969 will outline al-
ternative salinity control plans. Earlier studies by Pomeroy considered
the use of large evaporation ponds formed by diked areas within the
Sea (10). Such a scheme provides a salt outlet through salt extraction
from solar evaporation, thus stabilizing the salinity of the Sea.
If such a method were employed,the resulting salinity level of the
Sea would depend on pond size and the timing of such a project.
The nutrient content of the Sea is not greatly different from the
computed annual inflow; yet comparable annual loads of nutrients have
been entering the Sea for decades. Soluble forms such as NO-j have
not built up in the Sea over the past decades, but rather have been
converted to phytoplankton in the warm, shallow sea later to be
deposited as dead organic matter on the sea bottom or consumed by
predators within the sea. An equilibrium is maintained wherein
entering nutrients are assimilated by the Sea's ecological system or
deposited into the rich bottom sediments. Only a relatively small
fraction of the nutrients which have entered the Sea over the years
are maintained in the water phase.
Fish harvests, although sizeable, cannot account for these major changes
in nutrient level; for example, annual harvest of 100 Ibs. of fish
per acre would remove slightly more than one half million pounds of
nitrogen or about 2 percent of the annual nitrogen load (based on
2.5 percent nitrogen in fish flesh by wet weight). The estimated
Salton Sea harvest rate was about six pounds per acre in 1966.
In summary, the nutrient related problems of the Salton Sea are those
expected in highly eutrophic waters. The enrichment of the water
phase is probably as advanced as is likely in this inland sink where
nutrient trapping and the dynamics of the eutrophic ecosystem have
subdued the fertilizing effects of the rich tributaries. While
salinity increase is the most pressing water quality problem and a
task force comprising agencies of the State of California and the
Department of Interior is evaluating salinity control plans, work
is also in progress on plans for water level stabilization, nutrient
control and ecological protection for the Salton Sea.
75
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SUMMARY
The problems of Pyramid Lake, Nevada, and Salton Sea, California,
are similar in many ways and are common to othpr inland sinks.
Salinity increases and water level fluctuations attributable to water
and salt inflows and evaporation losses may be controlled or abated
through river basin and water quality management schemes. Pyramid
Lake water levels and the rate of salinity increases can be controlled
by increasing the water supply to the Lake. Salton Sea salinity and
water level problems can be better controlled by salt extraction,
lower irrigation efficiencies in nearby agricultural areas, bulkheading
on developed parts of the shore, and possible future evaporation
pond operation. Eutrophication symptoms, advanced in the Salton
Sea and emerging in Pyramid Lake, are less easily manipulated.
Natural forces of deposition and consumption of organic matter within
these waters will tend to limit nutrient buildup; however trapping
and predation effects alone will not eliminate algal blooms. Control
of eutrophication must begin with control or elimination of major
nutrient sources.
Although the quality of both the water bodies discussed is far from
"pristine," nonetheless both are economically valuable water resources.
The future of either is uncertain; however, it is clear that unless
water quality control measures are taken, both will eventually become
aqueous deserts. The problems of these two desert lakes are recognized
both locally and nationally. Local, State and Federal efforts are
underway to preserve or enhance the water quality and associated uses
of these two inland sinks.
76
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BIBLIOGRAPHY
1. HARDING, S. T. 1965 Recent Variations in the Water Supply of the
Western Great Basin. University of California Archives Series
Report No. 16, pp 226.
2. UNITED STATES DEPARTMENT OF THE INTERIOR, GEOLOGICAL SURVEY. 1967
Water Resources Data for Nevada, p. 114.
3. NEVADA FISH AND GAME COMMISSION. 1968. Data Tabulation received
from T. J. Trelease.
4. FEDERAL WATER POLLUTION CONTROL ADMINISTRATION. Water Quality
Survey of Pyramid Lake, Oct. 1968.
5. FISH AND GAME COMMISSION, STATE OF WYOMING, 1966. A Biological
Evaluation of the Lahontan Cutthroat in Eight Mile Lake, Carbon
County, Wyoming. Administrative Report. March.
6. La RIVERS, IRA. 1962. Fishes and Fisheries of Nevada. Nevada
State Fish and Game Commission.
7. U. S. DEPARTMENT OF INTERIOR, TASK FORCE. 1964. Action Program
for Resource Development, Truckee and Carson River Basins,
California-Nevada.
8. WALKER, B. W. 1961. The Ecology of the Salton Sea, California,
in Relation to the Sport Fishery, California Department of Fish
and Game. Fish Bulletin 113.
9. POMEROY, R. D. and CRUSE, H. A Reconnaissance Study and Preliminary
Report on a Water Quality Control Plan for the Salton Sea.
Prepared for the California State Water Quality Control Board,
December 1965.
10. ODUM, E. P. Fundamental of Ecology, W. B. Saunders Company, 1959.
77
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NATURAL POLLUTION IN ARID LAND WATERS
by
John M. Neuhold I/
If pollution is a degradation of the environment as a result of man's
activity in it, and if man is considered to be apart from the natural
environment, then the terms natural and pollution are clearly con-
tradictory. In this paper I explore the meaning of natural pollution
as it might apply to an arid lands water system, generalize a definition
for this pollution and speculate on the possible consequences of the
pollution thus defined. The water system we will consider will be
limited to the surface waters in arid lands, since these waters most
obviously reflect the effects of the meteorological contribution from
the hydrological cycle.
Characteristics of Arid Land Waters
Arid lands are characterized by a precipitation-evapotranspiration
ratio that favors evaporation. Under these circumstances, shallow,
standing bodies of water with a large surface area are not favored
except in endorheic basins where the input of surface water from the
watershed is at equilibrium with evaporation from the surface of the
basin. Such a permanent body of water is essentially a function of the
size of the watershed and characteristics of the catchment basin.
Aside from permanent bodies of water in endorheic basins, surface
water in arid lands exists primarily as streams or rivers. The water-
sheds are chacterized by shallow soil development and low vegetative
cover, a situation that favors substantial surface runoff. Sustained
flow in water courses in arid regions is the result of melting snow
packs at higher elevations or of sub-surface water flows in deep aluvia
or deeper aquifers. Because of the high degree of surface runoff when
precipitation does occur, waterflows in the streams are marked by
violent fluctuations in volume. In the higher order streams, they
can range from nothing to floods, and in the lower order, sustained-
flow streams it can range from low, clear flows to high, turbid flows.
Because of their relatively low mechanical stability, soils in arid
lands are highly susceptible to erosion. During periods of precipitation,
therefore, the surface flow is usually loaded with relatively high
concentrations of particulate matter which in turn increases the
corrosive quality of the water, and its turbidity. High evaporative
losses result in a concentration of solids dissolved from the geological
formations making up the watershed and the silt loads carried by
the runoff. In general, the sustained water flows in arid lands are
!_/ Director, Ecology Center, Utah State University, Logan.
79
-------
characterized by violent fluctuations in water level, high turbidities,
and a relatively high proportion of dissolved solids. Down stream,
salt concentrations and water temperatures are increased while
fluctuations in silt loads and waterflows are modulated.
An ecologist cannot discuss any aquatic system without also mentioning
its biological system. Every environment in the earth's biosphere
has a life system of one form or another developed in it. Waters
in arid lands are no exception. The remarkable thing about the life
systems in arid land streams are their adaptive qualities. Not only
is each life system geared to the violent changes in quality, but
the individuals making up that system are morphologically adapted
to sustain themselves under these violent changes. Fish, for example,
are morphologically adapted to cope with torrential flows and corrosive
silt loads. They are also physiologically adapted to handle sudden
changes in temperature and salt concentration.
Aquatic insects, the predominant herbivores in the system, are likewise
adapted morphologically and physiologically with timed stages of their
life cycle to "fit" the demands of the system. The primary producers
of the system, the algaes and diatoms, are perhaps most susceptible
to changes which occur. The scouring action of silt-laden waters
makes life for the primary producers somewhat tenuous. Although it
is not unreasonable to assume that a significant amount of primary
production does occur in these waters, it is also likely that terrestrial
sources supply quantities of organic materials via the surface runoff.
In any case, biological systems are important in arid land waters,
particularly relative to pollution, since it is the biological system
that first shows signs of the effects of that pollution. The aquatic
system thus is characterized by a specifically adapted biological
system that is a living, cycling pool of organic matter and nutrients,
and may serve as an indicator of pollution.
Uses of Arid Land Waters
Because of the scarcity in arid lands, water is much sought-after
for both consumptive and non-consumptive uses. Predominant uses
include irrigation, power generation, stock watering, community,
industrial, recreation, and navigation. Each of these uses has a
unique set of water-quality requirements. Those irrigating crops
and watering stock, for example, are concerned with the type and
quantity of salts. Power generation and navigation usage require
certain flow regimens. Culinary and industrial use must consider
the economics of treatment.
Pollution Defined
The subject of this discussion is natural pollution in arid land
waters. Pollution is variously defined depending upon man's use or
nonuse of the water. But most definitions agree that pollution implies a
80
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change in quality as a result of man's use. Similarly, the term
natural can be variously defined. It can include or exclude the
influence of man.
The "I - Thou" Definition of Pollution
Since man is an inextricable part of the biosphere and must be
incorporated into any consideration of ecosystem dynamics, I prefer
to look upon natural pollution as including his effects. However,
since he is rational and in potential control over his actions, his
effect in the natural system must be given a set of continuously
variable values dependent upon the state of his technological
development. The most natural system, then, would include man in a
hunter-gather culture, whereas the least natural system would have
him in a high state of technological development.
Most conservationists would treat the natural environment as a dis-
continuous variable. Under their interpretation, natural pollution
could only be contributed by catastrophic geomorphic and meteorological
events. The only criterion for measuring that pollution V7ould be
a change in the precatastrophe ecological system. Such events could
include volcanic activity, sudden and abrupt faulting resulting in
changes in water courses and sudden and abrupt changes in weather
patterns. Man's role in the environment defined as most natural
is relatively minor. He serves as a top carnivore with a limit to
population size dependent upon the production of the land area.
Development toward an agrarian-herdsman culture results in an increas-
ingly intensive use of land by man, with concomitantly increasing
effects upon the waters of that region. More use of the watershed
by grazing animals under man's control, and his development of culti-
vation and irrigation practices increase erosion probabilities and
thus the silt loads of the streams. Irrigation increases the total
dissolved solids in the waters returned to the natural system. In
addition, human populations densely congregated and their associated
effluents become more of a factor in the ecosystem.
If we follow the development of man into an industrial culture, we
find additional uses of the lands including extraction of mineral
resources from the watersheds, intensification of man's activities
on those watersheds, and more conditions conducive to changes in the
quality of water in the area.
At the existing state of technological development, man's use of an
ecosystem becomes more pervasive through the adding of contaminants
to the atmosphere, which in turn are precipitated upon watersheds
and contribute qualities to that watershed previously not present.
These eventually are reflected in the stream collecting systems.
For example, consider chlorinated hydrocarbons, which though used
primarily in areas quite remote from arid lands, can find their way
through meteorological sources onto the watersheds and eventually
into the streams.
81
-------
As I am defining natural pollution, it is a function of the state of
technological development of the human population on earth. Man is
part of the system. Taking Martin Buber's words, man is the "I" and
the environment is the "Thou." Note that pollution is considered to
be whatever is added to the water that causes a change in the ecological
system developed there. This definition admits man into the system
and allows for the development of a naturalistic ethic that man is
fully capable of imposing upon himself. In other words, as an ethic
is developed, the effect of technology may be reduced and the eco-
system becomes the true criterion for pollution identification.
The "I - It" Definition of Pollution
If any ethic has developed however, it is founded on the egocentric
viewpoint of material gains from watershed and water (man is the "I"
and the environment is the "It"). Thus our definition of pollution
must incorporate the use-oriented value system. In other words, water
can or cannot be polluted relative to the use to which it is put and
not relative to the system (including man) that has developed under
most natural conditions. Therefore, if arable lands are available
at the terminal ends of arid land systems, but the water arriving there
is too salty for irrigation use, the water is polluted in relation
to that potential use. Or the water is polluted when it is too silty
for industrial use even if the water at that point in space and time
had received its salt and silt loads in a "natural" way.
In this context, "natural" is considered to be any influence on water
quality not caused by man. Salty water from springs, silt from pristine
watershed, wildlife fecal contributions are examples of "natural
pollution." The problem with this definition of natural is that
natural salt springs contribute insignificant amounts of salt to the
surface water, pristine areas no longer exist and no population of
wildlife has escaped the influence of man. For example, some duck
populations around the Great Salt Lake are several magnitudes greater
in numbers now as a result of marsh management and agriculture, than
they were in early pioneer days. Certainly, the nitrogen input into
the marshes via duck droppings has also been increased.
Conclusions
There is virtually no arid land in this world that does not support
some form of man's activity. Certainly irrigation technology has been
widely applied to arable lands. Stock raising predominates over great
portions of arid and semi-arid watersheds. Many of the arid lands
are also rich in minerals and other geological deposits of value to man,
and therefore mined. Man's activities in arid lands require road
construction; therefore, surface disturbance results. Power generation
requires the construction of dams on the rivers and these change the
quality of the water below the dam as well as above. In the context
of our first definition of natural systems, these activities produce
a semi-natural type of pollution that nonetheless falls into the
category of natural.
82
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Despite technological development, arid lands in North America are
still sparsely populated. Intensive agriculture and industry and urban
settlement involve only small portions of the total arid land use.
However, whatever water is present in such areas is sure to be polluted
regardless of the definition used. Any additional use of an arid land
watershed produces materials sufficiently different from that which
would have occurred under the existing use to qualify as pollution.
From geological sources, one can expect increased concentrations of
salts of various types, including the heavy metals and increased
turbities. Mining activity brings minerals to the surface that
eventually may find their way into the stream courses and cause con-
siderable damage by producing toxic concentrations of elements that
are deleterious to the ecological system. Certainly this occurs when
mined minerals are upgraded and the liquors of the upgrading process
are released to the stream courses. Meteorological sources will bring,
in addition to the precipitation, airborne pesticides and other
organic and inorganic effluents of industrialization, some of which
may be in sufficient quantity to be toxic to components of the
aquatic ecosystem. Grazing activities tend to reduce plant cover,
and if not managed properly can denude the watershed resulting in
increased erosion and subsequently increased silt loads. Intensive
concentrations of grazing animals near watersheds produce quantities
of organic nitrogen compounds. Irrigation use of water results in
increased salt concentrations of the returned effluents. The lower
Colorado River provides a good example of such phenomena. All these
contributions to the aquatic system affect the "naturally" evolved
ecological system. At the same time, they also affect other uses
of the waters downstream.
Dams constructed on the main streams of arid lands have done a great
deal to reduce turbidities and regulate flows. The effects produced
on the ecosystem in the forbays and on water quality for long stretches
downstream from the dams have been great. The existing ecological
systems of these streams were essentially wiped out and other systems
replaced them. Further, the dams have allowed the lands under their
influence to accommodate greater numbers of people. Greater numbers
of people, in turn, contribute more effluents to their environment.
The net result has been that the streams must bear the effluents from
that increased population, which affects the area's newly developed
ecological system, man included.
The distinction between our original two definitions are important.
In the first, man is considered part of an ecosystem which he can
manipulate but only to the limit of available resources or to levels
of limiting factors before collapse of the system results. As Marston
Bates points out, man is part of a continuous and interrelated network
of life that makes him as natural as an algae. What affects the
system affects him. In the second definition, man sets himself apart
83
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from the system. He manipulates it to maximize his immediate economic
gain. In the first, an ecological ethic of land and water use is
inherent. In the second, it is nonexistent.
The ramjet process of people begetting development begetting people
is limited in arid lands by the availability of water. Unless an
ecological ethic is developed and implemented by man for the use of
these waters and the associated land areas, man may find himself to
be the factor limiting his own existence.
References
Bates, Marston. 1960. The Forest and the Sea. Random House, Inc.
Buber, Martin. 1958. I and Thou. Charles Scribner Sons.
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DISTILLATION OF WASTEWATERS: A WATER RESOURCE FOR ARID REGIONS
by
Allen Cywin, George Rey, Stanley Dea, and Harold Bernard •!•'
The use of distillation as a means of producing high quality water
in arid regions has previously be.en limited to applications using
saline waters as a feedwater supply, either from brackish ground
water or the ocean. Another potential source of distillation feed-
water in arid regions which should not be overlooked and may be
useable for distillation processes is the wastewater effluent from
secondary municipal sewage treatment plants.
Conceptual arrangements of how distillation may be used in wastewater
renovation schemes center about the concept of wastewater recycle.
Typical systems have been outlined by Hickman (1) and Stephan (2).
Both systems are based on'recycling for potable water reuse, some
or all the municipal effluent from biological secondary treatment
plants. These proposed systems are still conceptual, and remain to
be demonstrated. The system proposed by Stephan is shown in Figure 1.
Here distillation is used in a split flow manner in order to provide
the salt removal capability required for continuous water recycle for
potable reuse. In this plan pretreatment requirements before distillation
were not identified in detail.
An alternate to the potable water reuse plan by recycle would be the
production of low mineral content water for industrial purposes,
particularly for those industries which require such water in large
quantities. The scarcity of low mineral content water in many of our
arid regions currently requires high treatment costs for the water
sources available, if such treatment is not applied excessive maintenance
costs for machinery, boilers, piping, etc. are incurred.
A review of past studies (3,4) suggests that with the proper develop-
ment of a municipal secondary effluent conditioning process, this
source of water may be suitable for use as distillation process
feedwater. This very possibly results in less costly distilled water
as compared to the costs of conventional distillation processes using
saline water sources as feedwater. In addition, a part of wastewater
renovation costs can realistically be attributed to pollution control
requirements. This is particularly true in areas where tertiary
treatment of effluents may be necessary to meet water quality standards.
I/ Respectively, Director, Division of Applied Science and
Technology; Professional Engineer, Industrial Pollution Control Branch;
formerly Section Chief, Agricultural Pollution Control Section; and
Chief, Agricultural and Marine Pollution Control Branch, Office of
Research and Development, Federal Water Pollution Control Administration,
U. S. Department of the Interior, Washington, D. C.
85
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PRIMARY
TREATMENT
SECONDARY
TREATMENT
FILTRATION
ADSORPTION
IQi
ELECTRO-
DIALYSIS
CHLORINATION
\
RAW
WASTEWATER
CONCENTRATE
DISPOSAL
PRIMARY
TREATMENT
50%
SECONDARY
TREATMENT
SL
507,
FILTRATION
EVAPORATION
CONCENTRATE
DISPOSAL
ADSORPTION
ADSORPTION
POLISHI.1G
CHLORINATION
Total- 54^/1000 gal.
Figure 1 - Water Renovation Scheme
\
Total= 57^/1000 gal
86
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It is felt that for the immediate future, industrial reuse of municipal
effluents will take precedence over potable water reuse. This is
particularly true in view of the water needs for industry as forecast (5,6)
In addition, reuse for industrial purposes would have less stringent
health and safety requirements to meet.
Considerations
Renovating municipal effluents to meet the chemical requirements of
potable water standards can be accomplished by using tertiary treatment
processes for the removal of the remaining organic, ammonia, and
mineral constituents. In some cases the use of a demineralization
step may even be avoided by blending tertiary-treated effluents with
a lower mineral content municipal water intake. This approach was
outlined by Hickman (1) and can produce a product water of acceptable
mineral content in some cases. Such a method effectively reduces
the mineral content of recycled water by dilution.
In addition to the possibility of renovating effluents for potable
use, consideration should be given to renovating effluents for use
as an industrial water supply where a dissolved mineral content of
50 ppm or less is desired. It should be realized that the cost of
demineralizing effluents may well be competitive with the cost of
desalting brackish or saline supplies by the use of distillation.
In fact, a study by Gerster (7), indicated lower costs may be possible
if the maximum operating temperature could be raised to 350° F.
Research on the problems and costs of using effluents have been under-
taken by the Federal Water Pollution Control Administration (FWPCA).
However, more development work, and engineering demonstrations are
necessary in order to give potential users the necessary assurances
needed to implement effluent wastewater recycle or reuse for producing
high quality water.
An important consideration for the attractiveness of municipal
effluents as distillation feedwater relates to the sulfate content.
Table I presents average sulfate concentrations for various types
of potential feedwater supplies in arid regions. It shows that
wastewater effluents are considerably lower in sulfate content than
either ocean or brackish waters.
The lower concentrations of sulfate and total dissolved solids in
wastewater effluents will permit less percentage blowdown in a
distillation system than with most natural brackish waters and far
less blowdown than with seawater. The net results will be more product
water and heat conservation. Approximately 25% of the feed in ocean
water must be used for blowdown versus an estimated 57. for waste
effluents because of lower sulfate and solids contents. Lower sulfate
contents of wastewater should also allow higher operating temperatures
to be used for evaporation, less extensive sulfate scaling, and
consequently lower potential cost of distillation per unit of water
distilled.
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TABLE I
SULFATE CONTENT OF WATERS
Approximate
Source Concentration, rag/1
Ocean 2700
Los Angeles - San Diego, Calif. 300
(Wastewater Effluent)
Tucson - Phoenix, Arizona 150 - 300
(Wastewater Effluent)
Buckeye, Arizona 50 - 1500
(Brackish Supply)
Stephan's prior prediction (2) on the role of wastewater effluents
for reuse indicates that the highest cost of renovating effluents for
use in a water recycle plan is related to the demineralization operation.
If we were to assume a hypothetical secondary effluent wastewater with
a mineral content (TDS) of 850 ppm (City of San Diego, half of South
Dakota, etc.) and we require a water of 50 ppm or less (therefore a
removal of greater than 800 ppm), it is our estimate at this time
that distillation of wastewater could, for large scale use, be economical,
corapetetive or even advantageous in comparison with other sources of
supply.
Using a 10-20 MGD demineralization capacity as a study case, the total
cost of distilled water production is estimated to be about thirty-
six cents per thousand gallons of effluent used. The cost includes
our best estimate of pre- and post-demineralization treatment require-
ments. On the basis of this estimate, it appears the distillation
process should be considered for wastewater renovation to produce
industrial waters requiring less than 50 ppm of dissolved mineral
content. In contrast, electrodialysis (ED), another method of de-
mineralizing wastewater, would be limited to producing water of about
300 - 500 ppm when used in an optimum manner (8).
In light of recent advances in thin-film distillation technology (9),
even further cost reductions may be possible. Particularly if long
tube vertical (LTV) distillation is utilized. For this type of plant
the blowdown ratio should be about 5% of the total flow when distilling
many municipal effluents. The recent development in higher heat
transfer coefficients for falling thin-film evaporative surfaces is
comparable to increasing the permeability of existing membrane
88
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demineralizing systems (ED or RO) by a factor of 3 to 4, with no
additional increase in power consumption or transfer area. It should
be realized that this relatively simple development took some eight
years to become a reality in spite of the fact that it was known to
be theoretically possible for years prior to initiation of development
work.
Also, to be given consideration is the quality of the distilled water
in terms of total dissolved mineral solids (IDS) content. It generally
is too good to blend into a lower mineral grade water supply, particularly
when low mineral content water is expensive to make and processes
for making it result in additional cost appreciably above the initial
supply used (assuming municipal water supply). A further consideration
is that the projected demand for lower mineral content water is
increasing considerably (10).
If a distillation-dehydration process (11) were to be used for treatment
of municipal sewage sludges, 0.5% of the total plant wastewater influent
could be recovered as a by-product distillate water. In such a process
the heat required for distillation would be obtained by incineration
of the dehydrated sludge. This example implies municipal sewage
wastewater has sufficient recoverable heat values to provide some of
the energy necessary to purify the per capita water consumption demand.
Our survey of sewage and refuse heat values coincides with those of
Burns and Roe (12) in which the heat values in municipal wastes (both
solid and liquid) on a per capita basis was found to be sufficient to
distill 25% of the total per capita water demand. The energy involved
is nearly (approximately 757,) enough to demineralize the per capita
wastewater effluent from 850 to 550 ppm using distillation in a split
flow water reuse plan (Figure 1).
Research and Development Requirements
In view of the considerations presented and initial studies (3,4,7,13)
on the application of distillation to wastewater renovation, R&D work
with distillation processes, as applied to wastewater renovation, should
be continued. The work of 0*Conner (4) is encouraging, and the problems
of ammonia and volatile organics identified in the study may hopefully
be resolved by further laboratory and pilot plant work. In view of
the potential for obtaining higher heat fluxes in the use of LTV
distillation vs. the multiple stage flash (MSF) system, pilot plant
or demonstration efforts emphasizing the use and further development
of LTV distillation systems is recommended. Particular attention
however, will need to be devoted to the feedwater pretreatment require-
ments and operating conditions for the first stage effect. Pretreat-
ment systems generally include deaeration - decarbonation devices, and
in some cases, as for boiler water preparation, include hot lime
softening within the deaeration operation. Thus, developing the
pretreatment system to provide for multiple functions and increased
effectiveness for organic and ammonia removal should be possible.
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For example, as shown in Figure 2, a countercurrent steam stripping
deaerator could result in producing the same chemical effects as the
"hot" lime process and thus precipitate temporary calcium hardness
as calcium carbonate while stripping carbon dioxide, oxygen, and
volatile organics. The carbonate precipitation naturally softens
the water but also can be expected to coagulate and remove suspended
and possibly dissolved organic matter on clarification. This should
reduce organic contamination of distillate further than that reported
by O'Connor and thereby further reduce the ammonia reportedly generated
by the hydrolysis of organic matter in the still bottoms.
It should also be obvious that secondary effluent saturated with
temporary calcium bicarbonate hardness may be ideal for treatment.
If insufficient temporary hardness is available, hot soda-lime processing
may be required. Another lime process alternative would be the
"cold" lime process to precipitate carbonate and free carbon dioxide,
followed by stripping ammonia in a deaerator tower. The incremental
cost for the pretreatment system as discussed should be reasonable
since the basic operations performed are akin to the requirements
for preparing distillation feed and is standard practice in many
boiler feedwater preparations. In case the ammonia in the effluent
is not stripped when treated, nitrification of the ammonia in the
effluent can be included as a requirement of the preceeding biological
treatment operation. Some work on the development of this pretreatment
technique to the extent necessary to permit its employment with the
LTV distillation process is currently being initiated.
Total Treatment Costs
Total cost estimates for renovating municipal secondary effluents
into a high grade industrial water supply are as follows:
Total Cost ^/lOOO gal.
A. Pre-Treatment 10 - 20 MGD Scale
1. Nitrification 1
2. Hot-Lime-Deaeration stripping and 2
clarification (incremental increase
over existing)
B. Demineralization
Un-0ptimi2ed (15 MGD) LTV (4) 30 (1961 Cost basis)
C. Post Treat & Disposal
1. Aeration 1
2. Chlorination 1
3. Brine disposal 1
TOTALS 36^
90
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MUNICIPAL
SECONDARY
WASTEWATER
EFFLUENT
DISTILLATION
SLOWDOWN
HEAT
EXCHANGER
CONCENTRATE
DISPOSAL
DEAERATOR
TOWER
CaC03 - ORGANIC
SLUDGE
(1) Hot Ltme Treatment Ca(HC03)2
CLARIFY
(2) Soda-lime Treatment Ca SO^+Na CO —
(3) Cold Lime Treatment Ca(HCO ) + CaO
C024O2+?
STEAM
FROM
DISTILLATION
TREATED
DISTILLATION
FEEDWATER
Na SO +CaCO
2CaC0
HO
Figure 2 - Distillation Feedwater Treatment
91
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Pre- and post-demineralization treatment costs are included based on
our best estimate of technical requirements for successful operations,
The "hot lime" operation as a distillation pretreatment step assumes
a substantial reduction of the organic matter in the feedwater would
occur. Nitrification assumes essentially a complete conversion of
feed ammonia to a stable nitrate salt.
Conclusion
On the basis of this literature review we believe -- "A New Look at
Distillation" (14), is in order in arid regions faced with providing
low mineral content waters for industrial uses.
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REFERENCES
1. Hickman, K. C. D., "Role of Distillation in a Treated Waste
Recovery Cycle." Jour. American Water Works Association, 55,
1120-1130 (Sept. 1963).
2. Stephan, D. G., "Renovation of Municipal Waste Water for Re-Use."
A. I. Ch. E., Jour. Chem. E. Symposium. No. 9 (1965).
3. "Advanced Waste Treatment by Distillation." AWTR-7.
4. O'Connor, B., et al., "Laboratory Distillation of Municipal
Wastes Effluents." Jour. Water Pollution Control Federation
(Oct. 1967).
5. "Why Water Shortages?" Power (June, 1966).
6. Weinberger, L. W., et al., "Solving Our Water Problems - Water
Renovation and Reuse." FWPCA, Dept. of the Interior (Aug. 1966).
7. Gerster, J. A., "Cost of Purifying Municipal Waste Waters by
Distillation." Public Health Service Publication, No. 999-WP-6
(Nov. 1963).
8. Harty, H., "Desalination of Sea Water: A Survey Paper." BNSA, 134
(Apr. 1965).
9. Lotz, C. W. "Thin-Film Distillation." Industrial Water Engineering
(Dec. 1965).
10. Calmon, C., "Water Purity in Perspective." Industrial Water
Engineering (Oct. 1967).
11. "The Choice is Yours." Carver-Greenfield Corp. Brochure.
12. "Use of Waste Heat for Production of Fresh Water." OSW, Dept.
of the Interior (Saline Water Conversion Report for 1965).
13. Middleton, F. M., "Flash Evaporation for Sewage Distillation and
Concentration of Wastes."
14. Ahlgren, R. M., "A New Look at Distillation." Industrial Water
Engineering (Oct. 1968).
Additional References:
Anon, "Ion Exchange Now Purifies Even Saltier Water." Chemical
Engineering (June 1965).
93
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Brunner, C., "Pilot Plant Experiences in Demineralization of Secondary
Effluent Using Electrodialysis." Jour. Water Pollution Control
Federation^ Research Supplement (Oct. 1967).
Cywin, A., "Saline Water Conversion and the Demonstration Plant
Program." ASME, 60-SA-24.
Kunin, R., "A New Ion-Exchange Desalination Technique." First
International Symposium on Water Desalination, Washington, D. C.,
October 3-9, 1965.
Office of Saline Water, "Cost of Large Electrodialysis Plants." Dept.
of the Interior (Saline Water Conversion Report for 1965).
Schmidt, K. A., and Odland, K., "A New Ion Exchange Process for
Economical Brackish Water Desalination." Presented ACS Div. of
Water, Air, and Waste Chemistry, Detroit, Michigan (Apr. 1965).
Sturla, P., "Demineralization of Brackish Waters by Means of Ion
Exchange. " First Internation Symposium on Water Desalination,
Washington, D. C. October 3-9, 1965.
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ANIMAL WASTE RUNOFF - A MAJOR WATER QUALITY CHALLENGE
by
Anthony V. Resnik
and
John M. Rademacher —'
INTRODUCTION
The feeding of livestock in confinement has created a new major
industry. Having become firmly established in the United States by
the late 1950's, it continues to rapidly expand. During the emergent
stage, designers of cattle feedlots selected sites based primarily
on two criteria: drainage and accessibility. The lots were situated
on the nearest draw where the rains could scour the waste materials
from the lots into nearby gullies and streams. Since, traditionally,
animal wastes were considered as "natural" or "background" pollution,
control measures were not implemented. In the absence of positive
control measures, pollution of the surface waters resulted. Now it
is known that animal wastes contaminate water supplies, destroy fish
and aquatic life in streams, and generally degrade water quality.
More important, it is also known that animal wastes are a controllable
major source of water pollution necessitating immediate attention.
However, there are still gaps in our knowledge concerning the most
efficient, effective and efficacious means of controlling pollution.
This will require that we delineate specific research needed relative
to the expected trends of the feedlot industry. Not only must this
research answer the most pressing present problems, but also must be
simultaneously part of long range plans for developing sufficient
technology to control feedlot pollution 5, 10, or 25 years from now.
For instance, the interregional adjustments (shifting of location),
size, density and other factors are of vital importance in planning
research activities. We must, as accurately as possible, project
these adjustments.
Prevention and control of animal waste pollution cannot wait while
all the data are collected and assembled. To wait for all the answers
before taking action would squander time that we do not have. To
wait may mean the degradation of many waters beyond the point of
recovery with accompanying health hazards of undefined proportions.
To quote Robert H. Finch (1), "echoing Aristole, that the ultimate
end....is not knowledge, but action. To be half right on time may
be more important than to obtain the whole truth too late."
\l Sanitary Engineer and Director, respectively, Missouri
Basin Region, Federal Water Pollution Control Administration, U. S.
Department of the Interior, Kansas City, Missouri.
95
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Increased control is imperative now. To date, the kaleidoscope of
alternatives to animal waste pollution control have been honored more
fully in principle than in practice. Feedlot runoff could be greatly
reduced with a minimum expenditure by utilizing known information.
The majority of feedlot operators have not used techniques which
minimize the quantity and strength of runoff waste. For instance,
research has shown that feedlot runoff may be reduced by adjusting
stocking rates and utilizing optimum feedlot surfaces (2,3). What
does the future portend? Is it possible that animal wastes and city
garbage disposal may both be operated on a public utility basis (4)?
Furthermore, is this the mechanism to bring together an entire animal
production unit to research methods for the utilization of these
products?
A much broader view of waste management may be dictated by socio-
economic changes. While the return of the wastes to the land may
not be competitive with commercial fertilizers on an immediate crop
production basis, it may be highly profitable in terms of public
welfare over both the short and long range to use these wastes to
reclaim marginal lands. We are losing approximately a million acres
of agricultural land each year as a result of urban growth, highway
construction, and other natural and man-made incursions into the
reserve of productive land (4). It is difficult to equate the true
worth to society for the reclamation of lands. Certainly it extends
much beyond the yearly crop production.
The residents of the arid and semi-arid regions realize the value of
water. Ground water in the semi-arid regions of the Southwest is
being mined at an unprecedented rate. For example, in some areas
of Arizona the water table is declining as much as 20 feet per year.
In many locations the quality of the water deteriorates as the water
table lowers. Much of the water now pumped in Central Arizona does
not meet minimum agricultural and public health standards (5). Since
the agricultural industry consumes the overwhelming portion of the
water used, it has the greatest stake in protecting and enhancing
water quantity and quality.
ANIMAL PRODUCTION
There are approximately 110 million cattle in the United States.
Dairy cattle outnumbered beef cattle in this country until 1942.
Since that time the upward trend in beef consumption, the downward
trend in milk consumption per capita, and the upward trend in milk
yield per cow have combined to shift this cattle population emphasis
to almost four to one in favor of beef — in just 25 years! Approx-
imately one-half of the two billion tons of livestock wastes produced
annually in the USA comes from animals in confined feeding. The
magnitude of the problem caused by feedlot operations is reflected
in the statistics for feeder cattle. Data compiled by Loehr (8)
show the waste population equivalent of feeder cattle is greater than
the human population in 17 of our 50 states.
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The Missouri Basin States of Iowa, Nebraska, Colorado, Kansas, Missouri,
North Dakota and South Dakota, feed approximately 50 percent of all
slaughter cattle. Iowa leads the Nation in the number of cattle and
calves on feed. In 1967, more than 4 million beef cattle were marketed
from Iowa feedlots. The majority of the cattle were in .small farm
feedlots. Only four percent were in feedlots of more than 1,000 head (9)
Nebraska ranks second with approximately 35 percent of the fed cattle
in feedlots of more than 1,000 head. Third is California, with an
average of 1,800 head per feedlot. There was an 87 percent increase
in cattle marketings in California between 1957 and 1963 with virtually
all the growth occurring in feedlots with 10,000 head or more capacity.
Texas, Colorado and Kansas, respectively, rank fourth, fifth and sixth.
The new glamour area for cattlemen is the Central and High Plains
areas, including parts of Kansas, Nebraska, Colorado, and the panhandles
of Oklahoma and Texas. A recent survey (1968) conducted by the
Southwest Public Service Company of Amarillo, Texas, enumerates 274
large commercial feedlots in a 42 county area in Texas, Oklahoma, Kansas,
and New Mexico. They have a total one-time capacity of over 1 million
head -- 300,000 more than the year before and almost a half-million
more than in 1966 (10). The Texas High Plains has become the center
of the rapidly expanding cattle industry, experiencing a remarkable
146 percent increase in cattle inventories between 1965 and 1968.
Fed cattle inventories for the State increased 66 percent in the same
three year period. The exceptional growth of the cattle industry on
the High Plains is attributed to an availability of feed, adequate
supplies of feeder cattle, an adequate transportation network, rapid
growth of irrigation wells, and a favorable climate. Livestock feeders
state that cattle performance is better at higher elevations where
summer nights are cool and humidity is low (11).
Surveys reported by Colorado, California and USDA during the early
growth of the commercial feedlot indicated that optimum feedlot capacity
ranged between 10,000 and 20,000 head. Today 30,000 head capacities are
routine with 40,000 to 70,000 head lots becoming more prominent in
the panhandle area of Texas. Thus, it becomes apparent that growth
is still a part of this industry (13). It has been estimated that
by the early 1970's, approximately 2,500 large commercial feedlots
in the United States will supply nearly 70 percent of all the Nation's
finished cattle (10). There does not appear to be an optimum size
feedlot. The continuous decline in costs with increases in size seem
to justify continued increases in the size of the lots. However,
additional studies considering both internal and external costs of
operation are needed (12). Studies to date have largely dealt with
internal costs -- tax benefits, buying advantages, and other external
factors have not been fully evaluated.
COMPOSITION AND QUANTITY OF RUNOFF
The runoff from cattle feedlots can be potent. Miner, et al, (3)
reported COD concentrations from 3,000 to 11,000 mg/1, ammonia nitrogen
concentrations ranged from 16 to 40 mg/1 and suspended solids ranged
97
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from 1,500 to 12,000 mg/1. These data provide a basis for an example
of the significant difference between population equivalent (PE)
values based on runoff and values based on manure production (10,14).
The oft cited PE values based on total animal production have little
meaning with regard to water pollution. What we are really concerned
with is the amount that enters ground and surface waters. If the
objective is to quantify the magnitude of the potential stream
pollution, PE values should be based on the strength and volume of
wastes which can enter a stream by storm water runoff rather than the
total manure production. Dague (14) cites calculations, for a given
set of conditions, which demonstrate the BOD actually contributed
to the stream is about five percent of the total BOD production of the
animal. Other investigators have made estimates of the total annual
pollution loads generated by runoff from feedlots. These investigators
also demonstrated the quantity and strength of the wastes which enter
the streams to be considerably less than that defecated by the animals.
Let us now attempt to place this problem into perspective.
Sixty-six thousand feedlots, ranging in capacity up to 100,000 animals
blanket 7 of the 10 Missouri Basin States. Animal wastes from the
more than 20 million cattle, 16 million swine and 7 million sheep
defecate wastes equivalent to 370 million people. Using the previously
cited 5 percent figure, then the magnitude of the stream pollution
from animal wastes is more than 18 million PE in the Missouri River
Basin. The human population of the Missouri Basin Region is 7.9
million. Thus, the calculated stream pollution from animal wastes
is more than twice the human population equivalent. We must use
caution in predicting and interpreting stream pollution from feedlots.
There are many variables which influence the effect of feedlot runoff
upon the receiving water course. Among these factors are the climate
of the region and the area and nature of the feedlot surface. Also,
the antecedent moisture condition of the accumulated waste and the
rate at which precipitation occurs are of primary importance in
determining the quantity and quality of runoff from a feedlot (2).
It has been noted by various investigators (2,10) that the greatest
pollutant concentrations are obtained during warm weather, during
periods of low rainfall intensity, and when the manure has been
dissolved by water soaking.
During warm, dry weather, especially in the semi-arid regions, the
most noticeable change in the deposited manure is evaporation of
moisture. The wastes become pulverized by the hooves of cattle. If
the accumulated waste on the feedlot floor becomes tightly compacted
and dry, it provides a relatively imperious barrier to the initial
rain, resulting in large quantities of organic runoff. However, if
the accumulated manure on the feedlot floor is slightly damp when
precipitation begins, it can readily absorb a large quantity of
rainfall at a rapid rate, resulting in lesser amounts of runoff during
the early stages of the precipitation. The dry, high altitude of the
Texas High Plains provides excellent drying conditions for the huge
quantities of feedlot wastes. During the summer months, the moisture
content of the finely pulverized dehydrated feces and urine solids
may go as low as 2 percent (2).
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It must be remembered, however, that generalizations concerning
feedlot runoff are necessarily lacking in precision. For example,
weather conditions alone can be quite important. Data reported by
Kansas State University indicated all pollutional parameters greatly
exceeded previously measured values during a heavy rainstorm with
lot surfaces wet when the rain began. Three inches of precipitation
fell during an eight-hour period. Suspended solids were 26,850
mg/1 in samples taken 2-1/2 hours after the storm began and 4 hours
later were 45,200 mg/1 (10).
EFFECT OF ANIMAL WASTE POLLUTION ON WATER QUALITY
Since feedlots have generally been located without regard to the
soil inventory and topographic characteristics, surface runoff to
streams with subsequent damage from high BOD wastes is common.
Infiltration of nitrates from manures to well waters is well documented (6,7)
Field disposal of large concentrations of manures can lead to contamination
of underground supplies.
Field investigations of fish kills and other water pollution episodes
substantiate that the degradation of water quality due to animal
wastes is indeed a serious matter. The release or runoff of these
wastes to surface streams during periods of rainfall produces "slug"
loads of the polluting material which can traverse the receiving
stream for many miles, kill all desirable aquatic life in its path,
disrupt or prohibit the use of the affected stream for water supply
purposes, and generally create public alarm (15). The slug flow and
resultant adverse effects of animal wastes can be felt hundreds of
miles from their point of entry. Spring rains in Kansas in 1967
washed tons of cattle feedlot wastes into receiving streams resulting
in fish kills and ruining the water supply of downstream towns (16).
Stream surveys were conducted on the Missouri River in June and July
of 1967 during and after a fish kill in the River. The following data
were obtained (16):
Kansas City, Missouri - The dissolved oxygen level dropped
to 1.5 mg/1 in the river water, and was less than 4 mg/1 for
11 days, and did not reach 5 mg/1 for 19 days.
St. Joseph, Missouri - At times, the dissolved oxygen level
was virtually zero and was less than 4 mg/1 for 7 days, and
did not reach 5 mg/1 for 15 days.
Jefferson City, Missouri - The dissolved oxygen content dropped
to 2.1 mg/1 and was less than 4 mg/1 for 7 days and remained
less than 5 mg/1 for almost a month.
The flow in the Missouri River at all three stations ranged from
approximately 80,000 to 260,000 cfs with an average of 180,000 cfs
at Kansas City. Based on the above flows and dissolved oxygen
deficiencies, the oxygen demand was equivalent to the waste BOD
from 80 to 120 million people. Approximately 3 million population
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equivalent is the maximum that can be accounted for from municipal
and industrial sources (16). Animal wastes are one of the prime
suspects for the large unaccountable pollution load.
Surface water supplies in Kansas have been seriously disrupted by
feedlot runoff pollution. One such incident is described by an
Official (17) of the Kansas State Department of Health:
"In 1967 one small Kansas community using surface
water as a supply source was forced for a period
of two weeks to treat water with the following
characteristics: ammonia content up to 20 mg/1;
BODg up to 75 mg/1; dissolved oxygen 0.0 mg/1;
total coliform count 4 million; fecal coliform
count 2 million, and total fecal streptococcus
count at 5 million per 100 m/1 sample. Additionally
the water was heavily loaded with pungent and
difficult-to-describe organic materials which
produced a finished water product highly offensive
to the senses of taste and smell. The city was
forced to use activated carbon and increase
chlorination by a factor of 10 in order to 'not-too-
successfully' continue operation of the water
treatment plant."
There is additional evidence that animal wastes are a major source
of water quality degradation. During the past year, an estimated
12 million fish were killed by pollution in our waters. This terrible
toll reflects only the actual kills discovered and reported. Many
more thousands of dead fish go unnoticed or unreported each year (18).
Thirty-six fish kills in Kansas streams were investigated by the
Kansas State Department of Health and the Forestry, Fish and Game
Commission during 1967-1968. Twenty-two of these were attributed
to runoff from commercial feedlots (19). Spring rains in Kansas in
1967 washed tons of cattle feedlot wastes into the receiving streams
killing an estimated 500,000 fish. This is not to say that fish
kills are unique to Kansas, but rather suggests a greater awareness
by Kansas officials of the pollution caused by animal wastes. Recently,
in Kansas, a large dairy herd was decimated after drinking from a well
polluted by the runoff from beef cattle waste. This dramatically
illustrates the serious contamination that can be caused by uncontrolled
animal wastes (8).
Animal waste pollution is not restricted to the Midwest; it is a
national problem. In early 1966, the Interstate Commission on the
Potomac River Basin reported (20):
"Every time it rains ... enormous amounts of animal
wastes are washed from farmyards into the river,
rendering it unsafe for swimming .. although only a
quarter-of-a-million people live in the river basin
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above Great Falls, it has been estimated that the
number of farmyard animals -- cows, sheep, pigs,
chickens, turkeys — is the equivalent of a human
population of 3.5 million. While most of the human
population is served by some sort of sewage
treatment plant, there is no comparable treatment
for the animal wastes."
Still another affected area is in the great Southwest. For example,
the residents of Milford, Texas, have brought numerous damage suits
involving pollution against a large feedlot located a mile from the
community (21). The rapid growth of the cattle feeding industry in
the semi-arid lands of the Southern and High Plains areas has resulted
in the concurrent development of major water pollution problems.
Numbers of cattle on feed and feedlots with a capacity of 1,000 head
or more increased five-fold in the Southern Plains since the mid 1950's (2)
The problem starts with the cumulative build-up of large quantities of
organic waste on cattle feedlots subjected to sporadic and intense
rainfall. Evaporation rates are high in summer and the limited rain-
fall (15-20 inches annually) comes in sporadic bursts over short time
periods and unless controlled, this runoff will enter the water courses.
One of the most pressing needs in water pollution control is to slow
the eutrophication rate of lakes (aging process) which is accelerated
by overenrichment from agricultural, industrial and municipal wastes.
Lake Erie is the most dramatic -- and potentially tragic — example
of oxygen depletion in the water caused by nuisance aquatic plants
filling the l#ke. Many other lakes -- large and small — are in the
same desperate condition but have not achieved the national recognition
afforded Lake Erie. Although other nutrient sources such as municipal
sewage and industrial discharges are big contributors to eutrophication,
the vast amount of manure being produced in this country is one of
the major causes of the killing of a lake or river by accelerated
eutrophication (22). Nitrates and phosphates cause eutrophication,
and manure contains both of these plant nutrients. They can be carried
by runoff into the streams or percolate through soils to enter the
waterways.
In Minnesota, attention to the problem of eutrophication was brought
forth by the study on the Big Stone Lake where preliminary investigations
indicate a large amount of the nutrients entering the lake is from
cattle feedlots. The Minnesota Pollution Control Agency stated (23)
"there are places in the country where three or four times as much raw
sewage enters our streams from animals as from human beings." Studies
on Lake Mendota near Madison, Wisconsin, points the accusing finger
at manure carried by spring runoff into the lake as the source of
unwanted nutrient enrichment and growth of water plants. Limnologists
see eutrophication taking place in other beautiful lakes in Minnesota
and other states (24).
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EFFECT OF ANIMAL WASTES ON GROUND WATER
In a statewide survey the University of Missouri analyzed more than
6,000 water samples in Missouri. Forty-two percent of the water
samples contained more than 5 parts per million as nitrogen nitrate (25).
In some counties in Northwest Missouri, over 50 percent of the wells
sampled contained sufficient nitrogen to be of concern in livestock
production. Data indicated animal manure to be one of the major
sources of nitrate in water supplies. There was a definite statistical
relationship between livestock numbers and shallow wells containing
nitrate.
Agriculture's effect on nitrate pollution of ground water was also
investigated in the South Platte River Valley of Colorado. Most of
the 621,000 cattle in Colorado feedlots (February 1, 1967) were located
in this valley. Data showed that nitrate under feedlots is moving
through the soil and into the ground water supply. Since the feedlots
are usually located near the homestead, they may have a pronounced
effect on the water quality from domestic wells. The findings that
water under feedlots frequently contained ammonium and organic carbon
cause further concern about the effect of feedlots on underground
water supplies (7).
ACCOMPLISHMENTS: KEYS TO THE PROBLEM
The culmination of comprehensive Federal water pollution control
legislation came with the enactment of the Federal Water Pollution
Control Act, Public Law 660, in 1956. This law is the basis for the
Federal role and responsibility in water pollution control and stresses
the recognition of the State responsibility in water pollution control.
The amendments represented by the Water Quality Act of 1965 and the
Clean Water Restoration Act of 1966 were extensive and far-reaching.
The official state enforcement agencies are assuming their responsibility
in animal waste control. For example, eight of the 10 Missouri River
Basin States have enacted or are now in the process of enacting,
feedlot regulations. Regulations are, in effect, the blueprints
for the animal waste control program. They act as a guide to planning,
construction and enforcement. Regulations are needed to ensure the
feedlot operator that the measures he is taking will guarantee a
reasonable tenure of operation. It is necessary that the operator
know the controls being installed are adequate, and secondly, that
frequent changes will not be sought by the official agency. Uniformity
which concurrently allows for flexibility must be built into the
regulations. Different requirements may constitute an economic barrier
and are especially confusing to operators conducting business in two
or more states.
The existing legislation pertaining to feedlot pollution control should
be thoroughly evaluated. Many of the basic concepts contained in the
regulations are sound. However, more attention should be directed
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to management practices which would prevent the wastes from entering
surface or ground waters. For instance, the percent removal concept
of municipal sewage treatment is not applicable to the control of
feedlot pollution. Cattle feedlot runoff is a highly concentrated
organic waste. The strength may equal that of normal domestic sewage
or may be 10, 100, 1,000 or more times greater. Feedlot runoff may
still contain, after treatment, as high pollutional parameters as
domestic sewage, before treatment, if percent removal is the only
criterion used for treatment. Therefore, a "residual" concept of
waste treatment is proposed; That is, acceptable treatment is that
which reduces the pollution to a prescribed level or residual which
would assure adequate treatment.
Our laws must give due consideration to the location of feedlots.
Feedlots have generally been located without regard to the soil
inventory and associated topographical characteristics. It may be
not only desirable, but also necessary, to employ zoning regulations
to prevent the encroachment of the animal population into urban
areas, as well as to prevent the encroachment of the human population
into the feedlot areas. Hawaii and California have shown the way
with the passage of land conservation acts. Basically, their legislation
prevents encroachment of urban development into agricultural areas
and also provides a more favorable tax assessment for agricultural
lands.
Regulations should also provide for a continuing, comprehensive
animal inventory, state by state, drainage basin by drainage basin,
which would provide definitive data on the character and composition
of agricultural effluents, points of discharge and other pertinent
information. Just as we census the human population, we must also
keep up-to-date inventories of animal populations.
Leadership in animal waste control is not limited to the official
agencies. Research has been underway in the state agricultural
experiment stations regarding the characterization, handling, and
utilization of animal manures since the turn of the century. The
U. S. Department of Agriculture and many other Federal and State
agencies are conducting studies related to agricultural pollution.
CONCLUSION
An enlightened public has shown in all fields of environmental
protection, including water pollution control, that it is willing
to pay, in dollars, the added costs of maintaining a high quality
environment, rather than risk its own destruction. Enlightened
leadership will continue to create its own consensus. This paper has
presented an overview of the causes and effects of animal waste
pollution on water quality. The extent of the problem as well as
the effects on surface and ground waters are illustrated with research
data. The present status of legislation in regulatory control of
pollution is discussed. Measures to strengthen present regulations
are proposed.
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Analyses of Cattle Feedlots to Reduce Water Pollution." Presented
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