ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
REVIEW AND EVALUATION REPORT
ON
PESTICIDE POLLUTION
OF THE
LOWER COLORADO RIVER, PARKER DAM
TO THE
SOUTHERLY INTERNATIONAL BOUNDARY
Prepared by
National Field Investigations Center-Denver
Denver, Colorado
May 1973
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ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
REVIEW AND EVALUATION REPORT
ON
PESTICIDE POLLUTION
O.F THE
LOWER COLORADO RIVER, PARKER DAM
TO THE
SOUTHERLY INTERNATIONAL BOUNDARY
Prepared by
National Field Investigations Center-Denver
Denver, Colorado
May 1973
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LIST OF ABBREVIATIONS
In the interest of brevity and ease of reading, the following
abbreviations are used frequently in this report:
OP - Organo-phosphorus compound or pesticide -
singular arid plural.
OC - Chlorinated hydrocarbon or organo-chlorine
compound or pesticide — singular and plural.
UR - Urethane or carbamate compound or pesticide -
singular and plural.
H - Herbicide - singular and plural.
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I. INTRODUCTION
Five major agricultural areas are located immediately adjacent to
the Lower Colorado River, in the reach which forms the Arizona-California
and Arizona-Baja California borders. The mild climate and constantly
available irrigation water supply lead to year-around cropping of these
lands. Production of two or three high—value crops per year, together
with climatic conditions which are very favorable to insect populations
and weed growths cause the areas to be subjected to extremely intensive
applications of pesticides. The highly developed irrigation drainage
systems are suspect of providing direct return of pesticides to the
Colorado River.
Investigations carried out by the Colorado River Basin Water Quality
Control Project staff in 1963 and 1968 showed that the inter—state and
international waters of the Colorado River downstream of Parker Dam were
polluted by agricultural chemicals including pesticides. These waters
are subject to the full range of uses, including domestic consumption,
in Yuma, Arizona, in at least 11 communities in Southern California,
and by communities in northern Mexico. Fish taken from these waters
were found to contain very high concentrations of DDT and its metabolic
products. Brain tissue from distressed fish taken from Lower Colorado
River waters during 1968 showed cholenesterase inhibition as high as
35 percent which is indicative of a high degree of stress.
Virtually no water quality data are available to indicate trends
in these conditions subsequent to the 1968 investigation.
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This report summarizes the findings of the earlier field investi-
gations, relates the information obtained through recent reconnaissance
activities, and suggests legal and technical approaches to control of
pesticide pollution in the subject waters.
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II. SUMMARY AND CONCLUSIONS
Pesticide pollution of the Colorado River, in the Yuma, Arizona,
area, was shown during 1966 and 1968 to constitute a serious hazard to
the fishery and to domestic and recreational users of these waters in
the United States and in Mexico.
In addition to the hazards shown by the 1968 investigation, to
exist in the immediate Yuma area and in Mexico, three major irrigation
drains discharge to the Colorado River upstream of Imperial Dam.
Pesticides contained in discharges from these drains are available for
transport, via the All-American Canal, to domestic water users in twelve
communities in Arizona and California.
Subsequent to 1968, water quality data pertaining to the subject
waters have not included information sufficient to permit evaluation of
the pesticide pollution problem. Within the five major irrigated areas,
between Parker Dam and the Northerly International Boundary, total
irrigated acreage and total applications of pesticides have increased
since 1968. Use of the long-lived organo-chiorine compounds has re-
mained nearly constant at approximately one million pounds per year,
while use of the shorter-lived, highly toxic organo-phosphorus compounds
has increased 18-fold to nearly 1.8 million pounds per year. More than
5 million pounds of these materials were applied to the croplands,
within the five areas, during 1972. These statistics indicate that the
hazards, documented and implicit, have not diminished and have probably
become more severe.
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Peak hazard to water users is believed to occur during the June-
October cotton growing season. More than one—half of the total yearly
organo-chiorine and organo-phosphorus applIcations are made during
this one-third of the year.
The ways by which pesticides reach the Colorado River are believed
to involve: (1) runoff from fields during infrequent summer storms,
(2) drifting and overspray during applications, (3) sub—surface drain-
age and tail water from irrigated fields, (4) dumping of excess mixes
and clean-up of application equipment along and into waterways, and
(5) direct application.
Control means and procedures, legal and technical, are available
through which pollution of the Colorado River by pesticides can be
minimized. The technical measures include improved farming practices,
optimized drainage of irrigated croplands, control of tail water,
judicious selection of the pesticides to be employed, elimination of
dumping and overspray, biological controls, integrated controls, and
treatment of drainage to remove pesticides. Legal approaches include
improvement of State statutes regulating pesticide use; application of
the National Pollutant Discharge Elimination System dscharge permt
requirements and other sanctions under the Federal Water Pollution
Control Act Amendments of 1972, such as, the toxic substances provision
and the emergency powers clause; punitive action through the Rivers and
Harbors Act of 1899 or the Federal Common Law of Nuisance; legal defi-
nition of responsibility, by irrigation districts, for the quality of
discharges from district owned and operated drains.
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A thorough documentation of the present pesticide pollution situation
within the Parker Dam—Southerly International Boundary reach is needed
to provide the evidence and emphasis which can be translated into effec-
tive control of sources.
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II I. DESCRIPTION OF AREA
The Lower Colorado River valley, downstream from Parker Dam is
characterized by broad flat flood plains of alluvium overlain by evenly
sorted Aeoflan soil. The soil is readily drained and is exceptionally
well suited to irrigated farming. The climate within the area is arid,
with rainfall of less than five inches and evaporation exceeding six
feet, annually. Runoff to this reach of the Colorado River occurs as
a result of infrequent thunderstorms and irrigation return flows.
Water quality, within this reach, degrades seriously because of
withdrawals and irrigation return flows. For example, mean total
dissolved solids concentrations increase from approximately 720 mg/i at
Parker Dam to 1,590 mg/i at the Northerly International Boundary. The
mean temperature of the stream ranges from 18°C at Parker Dam to 21°C
at the Northerly International Boundary. The pH varies from 7.7 to 8.1.
Throughout the reach, the stream is invariably supersaturated with
dissolved oxygen. Nutrients are in abundant supply, supporting nuisance
growths of algae and an excellent fishery.
The five major irrigated areas IFigure 1] are the Colorado River
Indian Reservation (CRIR), Palo Verde Irrigation District, Weliton-Mohawk
Irrigation District, Vuma Project-Valley Division, and Yuma Project-
Reservation Division. Each area is drained by one or more open drains,
of which all but one discharge to the Colorado River. In addition to
the five listed areas, the All-American Canal conveys water into the
Imperial Valley for domestic and agricultural use. There is no return
flow from the Imperial Valley to the Colorado River. [ The diversions,
canals, irrigated areas, and drains are shown schematically in Figure 2.]
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Figure 1. Areas of Pesticide Application
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‘PARKER DA lI
PALO VERDE O 1VERSION DA l I ’
PALO VERDE
IRRIGATION DISTRICT
PALO VERDE OUTFALL DRA
IMPERIAL VALLET
RESERVATION DIVISION
IIORTWERN
BOIJ I I DART
MQRELOS DAM’
•WELTON MOHAWK
PROJECT
DRAIN
GULF OF
CA Li F DRill A
Figure 2. Schematic of Irrigation Diversions and Drains-tower Colorado River
‘HEADGATE ROCK DAM
COLORADO RIVER
INDIAN RESERVATION
.CRIR UPPER MAIN DRAIN
i s a
CRIR -LOWER MAIM DRAIN
AL DAM
MODE 1
VILLE T
DIV ISION
ALAMO CANAL
MODE 3
NOT TO SCALE
— S
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Streamflow in the Colorado River main stem is highly regulated.
Delivery schedules, both to the .Anierican users previously listed and
to the users in Mexico, cause rapid and severe changes in stream stage,
velocity, dilution capacity, and quality. The waters within the subject
reach, the California service area, and in Mexico, are subject to the
full range of uses, including domestic water supply, primary and secon-
dary contact recreation, fish propagation, industrial, and agricultural.
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IV. AGRICULTURAL PRACTICES
A. General
Climatological conditions, excellent soil, and constantly available
water supply combine to create ideal growing conditions. Most of the
lands are cropped on a year—around basis. Major crops grown are alfalfa,
cotton, wheat, barley, corn, sorghum, lettuce, melons, citrus, and
grasses. Many lesser crops, including green vegetables, sugar beets,
and nuts, are also grown.
Flood irrigation is widely practiced; however, alfalfa and grasses
are occasionally spray-irrigated. The lands are all drained by open
drains to the Colorado River, but major differences exist in the drain-
age systems. Some lands are underlain by highly developed tile drainage
systems, some are drained by pumped wells, while others depend on
percolation and lateral movement to drains and streams. Lands drained
by tile systems are usually well leached, and the return flows percolate
quickly to the tiles, thence to the open drains. Lands that are de-
pendent upon natural drainage are usually less well—leached and can,
in fact, store salts from the applied irrigation water, and tend to
return drainage of poorer quality to the open drains. Most practitioners
of flood irrigation direct tail water (excess water reaching the down -
slope end of the furrows) to the nearest surface drain. The tail water
can carry large quantities of chemical residue, crystalized salts, and
debris, which has been picked up in the initial surge down the furrow.
B. Pesticide Applications
Except for similar areas in the Lmperial arid Coachella Valleys,
probably no other area on earth ! subjected to such intense applications
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of agricultural chemicals. Fertilizers are applied primarily by ground
rigs, while pesticides, including herbicides, are applied by means of
both ground and aerial equipment. In terms of water pollution, pesti-
cide applications upon lettuce and cotton are of particular concern.
Repeated and heavy applications of highly toxic chemicals are necessary
to control the variety of pests which plague these crops. Applications
upon other crops vary widely according to the form arid extent of infesta-
tions experienced from year to year.
In recent years, some shift toward a preponderant use of OP and
UR, as opposed to OC use, is evident. This shift has been brought
about by: (1) the banning of DDT and related persistent compounds,
(2) the need for more toxic substances to overcome tolerances attained
by some pests, and (3) the widespread belief by farmers, distributors,
and applicators that the shorter-lived OP are a lesser hazard to the
envi ronment.
OC use remains significant, particularly upon cotton. The total
pesticides and herbicides applied to croplands within the five subject
areas during 1972 are summarized as follows:
Class of Pounds Applied
Compound During 1972
Organo-phosphorus 1 ,794,000
Organo-chlorine 940,000
OP-OC combinations 192,000
Carbamates 1,106,000
Herbicides 1,169,000
Total applications in 1972 5,201,000
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By comparison, in 1968 approximately 1,000,000 lbs of OC and
100,000 lbs of OP were applied to the same areas. Use of UR was
essentially negligible at that time. Thus, use of OC has remained
nearly constant; use of OP has increased 18-fold; and UR use has
reached proportions comparable to total pesticide use in 1968.
The intensity of application, and thus the hazard to Colorado
River water users, reaches a peak during the four months of the cotton
growing season. Estimated use during the 1972 cotton season and the
percentage of the total application for the year are summarized as
follows:
Class of Pounds Applied Percent of
Compound July-Oct 1972 1972 Total
Organo-phosphorus 1 ,045,000 58.2
Organo-chlorine 506,000 53.8
Carbamates 455,00O 41.1
Herbicides 1i66,000 39.9
2,472,000 47.5
It is readily seen, from this summary, that more than one—half of the
OP and CC applications occur during one-third of the year. From the
water pollution control standpoint, this fact takes on added significance
because water applications and return flows also peak during this period.
Transport of pesticide residues to open drains and the receiving stream
is thus enhanced.
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V. THE LOWER COLORADO RIVER PESTICIDE POLLUTION PROBLEM
A. ys by Which Pesticides Enter the Stream
Pesticides find their way into open drains, canals, and streams
in several ways. These are believed to involve: (1) runoff from
fields during infrequent summer storms, (2) drifting and overspray
during applications to crops near canals, drains, and streams, (3)
sub—surface drainage and tail water from irrigated fields, (14) dump-
ing of excess mixes and the cleanup of application equipment in water-
ways, and (5) direct application to control aquatic weeds, rough fish,
and aquatic insect pests.
Storm runoff can be discounted as a major vehicle for pesticide
pollution within the subject reach, because of the infrequency of
runoff events. The other listed means by which pesticide pollution is
thought to occur are subject to viable controls, both legal and tech-
nical in nature. These control procedures and methods are discussed
later in this report.
B. The Hazards Associated with Pesticide Pollution
Organo-chiorine pesticides are highly persistent in the envi ronment.
For example, the half—life (time required for one-half of the amount
originally present to degrade) of chlordane is on the order of four
years. These compounds are toxic to fish and to warm-blooded animals,
and tend to concentrate through the aquatic food chains. When ingested
in sub-lethal quantities, these compounds are stored in the fat and
organs of animals, including humans. Thus stored, they become available
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in higher concentrations when fat is used during stress or low food
intake. The OC have been associated with many diverse damages to the
aquatic environment and have become ubiquitous in streams and oceans.
Organo-phosphorus compounds are related to and, in some cases,
derived from the war gases. In general , they are much more toxic and
much less persistent in the environment than are the OC. Their half-
lives are generally in the range of a few weeks or months. Their ex-
treme toxicity is attained through chemical inhibition of the enzyme
acetyicholinesterase in the nervous systems of animals. Certain of
these compounds are so highly toxic that skin contact, inhalation,
or ingestion of very minor amounts can bring on nervous collapse within
seconds and death within a few minutes. Minute amounts of these com-
pounds in a stream can produce massive fish kills. The hazards to
domestic water supplies and to waters used for contact recreation are
obvious. The effects of chronic sub-lethal doses of these compounds on
fish and warm-blooded animals has been the subject of much research,
though producing few applicable findings.
The carbamates are also highly toxic, but since they have extremely
short half-lives, they are generally considered a lesser hazard than
OC and OP. Herbicides are formulated to kill or retard growth of
plants. They are, however, toxic to animals in high concentrations.
In the subject areas of the Lower Colorado River Basin, a substan-
tial increase in the use of OP compounds has taken place in the five-
year period prior to 1973, although OC remain extensively used on cotton,
lettuce, and citrus. in terms of hazards to users of Lower Colorado
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River waters, employment of the longer-lived OC remains at levels
that can be expected to yield concentrations in water and in fish
similar to those reported in 1968. Moreover, use of a particularly
toxic OC, Toxaphene, has increased since 1968. As indicated earlier,
use of the shorter-lived OP has increased 18-fold since the 1968 in-
vestigation. This increase represents an unknown degree of hazard,
but one which has not diminished and which deserves careful considera-
tion and analysis. Water quality data collected within the subject
area since 1968 do not enable evaluation of recent pesticide pollution
cond I t ions.
C. Previous Studies
During the fall and winter of 1963—1964, the Colorado River Basin
Water Quality Control Project (PHS-DWSPC) carried out a limited evalu-
ation of pesticide concentrations in irrigation return flows. The
primary thrust of the effort was toward development of sampling and
analytical techniques. The work was discontinued prior to completion.
Alarmed by increasingly frequent fish kills, during the 1966-1967
period, the Arizona Game and Fish Department analyzed samples of flesh
and viscera from fish taken from waters of the Colorado River near
Imperial Dam. These samples were found to contain very high concentra-
tions of DDT and other OC compounds. One fish sample from Mittry Lake
was found to contain 92.5 parts per million IDE, a decomposition pro-
duct of DDT. Another sample obtained from the Yuma Project-Valley
Division main drain contained 36.8 ppm Toxaphene.
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In 1968, the Colorado Project (FWPCA) again initiated limited
studies of pesticide concentrations in the Colorado River at the
Northerly International Boundary; the Yuma Project-Valley Division
Main Drain, near San Luis, Arizona/Sonora; and at the intake of the
Vuma, Arizona, Municipal Water Treatment Plant. This study was
seriously impaired by the limited number of samples that could be
analyzed employing techniques and equipment then available. Never-
theless, high concentrations of pesticides were measured. Azodrin,
Toxaphene, and Parathion were recovered in almost every sample analyzed.
More than 60 percent of the water and carbon-adsorption samples from
the three points exceeded the NTAC* Water Quality Criteria for fresh
water organisms. Numbers and types of samples exceeding the criteria
are summarized as follows:
Liquid Composite Carbon-Adsorp—
Total Samples tion Samples Percent
Samples Exceeding Exceeding Exceeding
Analyzed Criteria Criteria — Criteria
Vuma Water Treatment
Plant intake 23 4 5 39
Colorado R at
Northerly Intl
Boundary 26 7 6 50
Vuma Proj Main
Drain at Southerly
Intl. Boundary 22 8 100
[ Average, maximum, and minimum concentrations of total organo-phosphorus
and organo-chlorine pesticides and the sums of the quantities determined
during this survey are presented in Table I.]
* Acronym for the National Technical Advisory Committee to the Secretary
of the interior.
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Table I. Summary of Pesticide Concentrations
1968 FWPCA Survey
•Carbon Adsorption Columns
S tat i on
Colorado R at
Northerly Intl.
Boundary
Organo-phosphorus
Compounds
(ng/F)
Avg . Max. Mm .
260 818
Organo-chiori ne
Compounds
(ng/l)
Av Max. Mm .
Tot a 1
Insecticides
(ng/l)
Avg. Max. Mm .
3 1422 1 ,540 65
Yuma Proj Main Drain
at Southerly Intl.
Boundary
540 976 271 279
1,053 23 819 1,519 244
Colorado R at Yuma
Water Treatment
Plant Intake
76 314°
9 89 270 0 165
610 19
Composite Water Samples
Colorado R at
Northerly Intl
Boundary
430 3,370
0 145 1,120 0 548 3,370 140
Yuma Proj Main Drain
at Southerly Intl.
Boundary
260 1,178
0 710 1,850 83 970 2,578 303
Colorado R at Yuma
Water Treatment
Plant Intake
50 162 722
218 1,519
0 114 200 0 232 1,519 10
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For the past ten years, fish kills have been a characteristic of
the Colorado River within the subject reach. Many of the kills have
been associated with pesticides. During the 1968 survey, four fish
kills occurred, afl of which were associated with high concentrations
of pesticides in the waters in which the kills occurred.
The study showed that a serious hazard to the fishery and to the
domestic and recreational water users, in the Yunia, Arizona, area and
in Mexico, existed during the period of the investigation.
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VI , LEGAL AND TECHNI CAL APPROACHES TO CONTROL OF
PESTICIDE POLLUTION IN THE LOWER COLORADO RIVER
A. Licensing of Applicators
The States of Arizona and California, between which the Lower
Colorado River forms the boundary, license and regulate pesticide ap-
plicators. The regulatory proviSions deal mainly with labeling and
registration of pesticides, safety to handlers and applicators,
allowable residues on produce and similar matters. There are no limit-
ing concentrations for pesticides in irrigation tail water or drainage
that enters surface streams. The regulations provide no buffer zones
for the protection of surface waters from drifting of sprayed materials.
The dumping of unused mix and cleaning of equipment in irrigation canals
or drains which discharge to surface waters and the disposal of pesti-
cide containers is not addressed. Similarly 1 discharges of pesticides
by formulators are not controlled by the regulations. The statutes do
not provide the mechanism for surveillance and enforcement of the regu-
lations. In summary, the State pesticide regulatory apparatus in both
Arizona and California can be considered to be ineffective in the pre-
vention of pollution of surface waters by pesticides.
B. Applicable Water Quality Standards
Both Arizona and California Water Quality Standards have been ac-
cepted by the Secretary of the Interior (EPA Administrator) and are,
therefore, Federal Standards. The Standards do not relate to specific
discharges and are, thus, virtually useless in the abatement of pollution
by pesticides. Extracts of each Standard pertaining to pesticide pollu-
tion are as follows:
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California
“3. Biocides
Biocide concentrations in Colorado River waters
shall be kept below levels which are deleterious
to domestic water use and to fish and wildlife.”
Arizona
“8. Biocides
Biocides have been the subject of much discussion
in the past 1 and probably will be discussed for
many years. Prudent use of biocides has enabled
our agricultural industry to provide ample
food and fiber products for our high standards
of living. Esthetically, we can have better
gardens and a more healthful existence because
of biocides. Uncontrolled use of biocides is
not beneficial, and should not be allowed.
Generally speaking, biocides are expensive, and
over appl ications are seldom made. Discharges
of wastes containing biocides from manufacturing
and tank cleaning operations must not be allowed.
“More research and study of the cumulative effects
of biocides on humans and wildlife must be made,
and appropriate safeguards applied as standards
for the waters of the State.
“Types and effects of biocides are too numerous
and varied for tabulation. Further, the
intricacies and variations of technical analysis
for biocides presently defy the prescription of
any one or a few tests for their detection or
determination (L 1 ). Bio-assay tests can be used
to establish allowable limits for biocides.
“Application of biocides in agricultural opera-
tions which could result in biocide levels in
waters of the State which are deleterious to
human, animal, plant or aquatic life shall be
subject to abatement. Mere detection of a
biocide in the water is not cause for abatement.”
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C. Federal Water Pollution Control Act Amendments of 1972
A number of legal theories are available to abate pesticide pollu-
tion of the Lower Colorado River which is a navigable waterway of the
United States and within the jurisdiction of the Federal Water Pollu-
tion Control Act (FWPCA) Amendments of 1972.
The FWPCA Amendments of 1972 clearly apply to pesticides since
the term “pollutant,” among other things, means “industrial, municipal,
and agricultural wastes discharged into water.” Tail water, tile drain-
age and dumping involve conveyance of pesticides into the waterway
through a discrete channel and, therefore, a “point source” as defined
by the Act. These discharges contain pollutants which are prohibited
by Section 301, unless the discharge is controlled by a National Pollu-
tion Discharge Elimination System (NPDES) permit. The permit, if granted,
can be so conditioned so that pesticides are removed or otherwise rendered
innocuous.
In order to meet the intent of Congress in controlling pollution,
the “discharge of pollutants” should be given a broad definition. This
is somewhat justified since agricultural waste is specifically included
within the pollutant definition. Broadly construing the definition of
“point source” it can be argued that certain farm areas where highly
toxic pesticide concentrates are applied could be considered as point
sources just as “concentrated animal feeding operations” are within the
point source definition. Portions of an irrigation district would then
not only be subject to the effluent requirements of the Act but also
the NPDES.
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The discharge of toxic substances is prohibited by FWPCA Section 301
except as it may be in compliance with Section 307, the toxic substances
provision. Section 307 provides for regulations for toxic substances
effluent standards, These have not been promulgated. Therefore, any
discharge of toxic substances is prohibited until to1 rable effluent
standards are established by regulations. As the regulations are
adopted, discharge of toxic substances may be permitted only within
those limits. Section 307(d) prohibits the violation of any of these
standards by any source which would include non-point sources.
The L 02(k) immunity from prosecution under either the F 4PCA or the
Refuse Act does not apply to Section 307, toxic and pretreatment standards.
Therefore, enforcement prerogatives are available to the EPA, under the
FWPCA, once the toxic substance list has been promulgated. Congress in-
tended, however, that dangerous and toxic substances be abated as soon
as possible, even before discharges were limited by the promulgation
of standards. In those circumstances EPA may seek injunctive relief
against such pollution under Section 5Q1 , Emergency Powers.
The Emergency Powers provision provides that “the Administrator,
upon receipt of evidence that a pollution source . . . is presenting
an imminent and substantial endangerment to the health of persons or
to the welfare of persons where such endangerment is to the livelihood
of such persons such as inability to market shellfish, may bring suit...”
The first category of cases would generally be confined to endangerment
of drinking water supplies or threats to humans using designated recrea-
tional areas. The second category would include short-term as well as
long standing pollution problems where shellfish and other income pro-
ducing aquatic life are being substantially affected.
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This provision is intended to be supplementary to and not a sub-
stitute for the regulatory provisions of the Act. However, the Congress
recognized that from time-to-time continuous discharges occur which
present an imminent and substantial endangerment to persons or to fish
and wildlife. It is the Congressional intent that these discharges
should be abated through this authority.
If certain pesticides can be categorized as “hazardous substances”
within the meaning of FWPCA Section 311(a) 1i their discharge may be
absolutely prohibited. It is quite doubtful that substances which are
registered under the Federal Insecticide, Fungicide, and Rodenticide
Act will appear on the hazardous substance list to be promulgated by
the Administrator.
D. Rivers and Harbors _ Açt of 1899 -Refuse Act
The Refuse Act prohibits the discharge without a permit of refuse
to the navigable waters of the United States. Courts throughout the
country have repeatedly held that the discharge) directly or indirectly,
of pollutants such as pesticides is a violation of the Refuse Act.
Upon conviction 1 dischargers are subject to civil and criminal penalties
under the law. In the irrigation districts adjacent to the Lower
Colorado River, irrigation drainage is collected by the districts and
discharged to the River. Open drains are subject to dumping of unused
pesticide mix, contamination from clean-up of equipment, drift from
aerial and ground spray applications, and direct application of chemicals.
The discharge of these pesticide laden waters to the Colorado River, a
navigable stream, is clearly a violation of the Refuse Act and is sub-
ject to criminal or civil penalties.
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Acceptance of irrigation drainage containing pesticides by irriga-
tion districts places each district in the position of knowingly aiding
and abetting, authorizing, and instigating a violation of the Refuse Act.
Litigation growing out of a comprehensive investigation of pesticide
pollution in the Lower Colorado River Basin should charge the farmers
and applicators as well as the irrigation district involved. As a
result of such a class action, it should become clear to the irrigation
districts, the farmers, and the applicators that they must police the
application of pesticides within the irrigation district.
The Refuse Act, then, is available to abate pesticide pollution
of the Lower Colorado River even though the source is indirect in
nature. The important point is that pesticide refuse is reaching a
navigable waterway which is statutorily prohibited. The 1t02(k) immunity
provision of the FWPCA Amendments of 1972 is no defense, since toxic
substances are not included in the exclusion.
E. Federal Common Law of Nuisance
The Federal Common Law of Nuisance could also be utilized to abate
pesticide pollution in the Lower Colorado River Basin. In an April
1972 Supreme Court decision, Illinois v. City of Milwaukee , 4ERC 1001,
the Court stated that “The application of Federal Common Law (nuisance)
to abate a public nuisance in interstate or navigable waters is not in-
consistent with the Water Pollution Control Act.” Although the Supreme
Court had reference to the FWPCA prior to the October 18, 1972 amendments,
the same application could be made to the new law. This “new and im-
portant legal remedy” has been used by the Justice Department in a number
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of cases since the Supreme Court decision. For example, Reserve
Mining, Whittaker Corporation, and the City of Memphis, etc. This
legal theory could be utilized concurrently with the above mentioned
approaches.
F. Physical Control Methods
Experimental work and research has shown that pollution of surface
waters as a result of pesticide applications can be greatly reduced or
eliminated through carefully designed drainage systems, carefully con-
trolled irrigation practices, and intelligent farming practices.
Tail water is excess water that reaches the downslope end of each
furrow when flood irrigation is practiced. This tail water is deliber-
ately routed to the nearest surface drain. Tail water usually carries
large quantities of pesticide residue, crystal ized salts, and debris
picked up in the initial surge down the furrow. This source of pollu-
tion of surface waters can be minimized or eliminated by the careful
application of irrigation water so that no tail water is created or
through the disposal of tail water by ponding, evaporation, and infiltra-
tion.
Much of the irrigated farm land in the Lower Colorado River Basin
is drained by deep tile drain systems. Water that percolates past the
root zone remains in contact with the soil column of at least 2 meters
(6 ft) before reaching the tile drain. Experimental work carried out
in the Cochella Valley, in 1968 and 1969, confirms earlier laboratory
research which indicates that OC and OP pesticides are adsorbed on soil
particles during percolation through the column. Although long-lived
OC can subsequently be leached from the soil and continue through the
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drainage system to reach surface waters, the deep drainage systems are
effective in limiting the return of organo-phosphorus compounds. It
has further been shown that repeated applications of OP to the same
fields results in reduced quantities of residual material reaching
deep tile drains. Acclimation and buildup of tolerant soil bacteria
which can degrade the short-lived organo-phosphorus compounds is pre-
sumed to be the cause of this reduction in yield. Similar investiga-
tions have been reported pertaining to carbamates.
Recent research discloses that concentrations of organo—phosphorus
compounds recovered in tile drains is reduced markedly by increasing
the time lapse between irrigation water applications. Thus, careful
timing of irrigation applications provides additional possibilities
for reduction of pesticide pollution in waters receiving irrigation
drainage.
it is clear, then, that the judicious selection of pesticides to
be used (discussed later herein) , properly designed deep drainage
systems, and proper timing of water and pesticide applications can
reduce the quantities of pesticides reaching surface streams via irri-
gation return drainage.
Dumping of unused pesticide mix and the clean-out of pesticide
application equipment in irrigation drains and canals is believed to be
a major source of pesticide pollution in the Lower Colorado River system.
The relatively high concentrations and the slug nature of this mode of
pesticide pollution combine to create the potential for serious hazard
to human health and welfare, and to aquatic life. No satisfactory method
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has been employed for prevention of this activity in the Lower Colorado
River growing areas. Possibility for control range from elaborate
schemes for the tagging of pesticides with dyes or trace elements
through equally elaborate schemes of sealing and centralized inspection
of application equipment. In any event, State and local governments
must adopt statutes which provide for meaningful punitive recourse
against dischargers of pesticides and must provide for enforcement of
those statutes. Additionally, if irrigation districts are to function
as collectors and dischargers of irrigation drainage, they must assume
responsibility for quality of the discharge. Irrigation districts have
not, at this time, assumed nor been granted the police powers necessary
to prevent the introduction of pesticides into the drainage. Enabling
legislation is probably necessary.
Cotton is the principal crop grown in the Lower Colorado River
farming areas, and the susceptibility of cotton to pink boliworm in-
festation causes the cotton crop to receive extensive applications of
various pesticides. Much work has been done and is being done on methods
of control of pink boliworm infestation that would reduce the necessity
for application of pesticides. These methods include biological con-
trols (discussed later herein) and the interruption of the biological
cycle of the pink boliworm. The pink bollworm is particularly vulner-
able during larval stage and diapause. interruption of the cycle during
these stages can be attained by the burning or shredding of cotton
stalk immediately after harvest, deep plowing with a mold board plow
at the earliest possible date, filling of cracks and crevices in the
soil after plowing, and two irrigations seven to ten days apart shortly
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after plowing. Early harvesting and clean picking are also extremely
important in preventing the emergence of egg laying moths in the
following spring. Such control programs might require the impetus of
regulatory action. Concerted information programs within irrigation
districts could minimize the necessity for applications of hazardous
pesticides.
Q. Biological Control
Biological control holds substantial promise for reduction of pest
insect population without application of dangerous chemicals. At the
present time three techniques are in the experimental stages. The
first of these involves the sterilization of the males of the target
speci s such as pink boliworm and screw worm. The sterilized males are
broadcast by the millions in infested areas where they mate with normal
females which then lay non-viable eggs. This technique has been suc-
cessful in the virtual elimination of screw worm populations in the
southwest.
The second technique involves the enhancement of populations of
parasites. Experimental work has shown that wasps can be effective in
controlling populations of insects such as the pink bollworm. The
female wasp attacks and kills the target organisms and deposits her
eggs in the carcass. Upon hatching, the young wasps use the carcass
for food and as they reach adulthood, the cycle is repeated. Other than
their nuisance factor, wasps are harmless to man. Their prolific nature
causes them to be useful in the protection of crops from insect pests.
Experimental and test-scale work employing other predator parasite organ-
isms is underway at and by a number of research organizations.
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A third method of biological control, already experiencing success
against insect pests on lettuce, kale, and similar crops, is the Bacillus
organism. The material applied is a bacterial culture whichis antag-
onistic to a specific pest. A brand name now in routine use is Thuricide.
H. Chemical Controls
Until physical and biological controls can be made completely effec-
tive, applications of chemical pesticides wfll continue. The effects
on water quality can be minimized through judicious selection of the
chemical to be used. OP and UR compounds are readily degraded in the
environment while OC are extremely persistent. The acute and chronic
toxicity levels of the OP compounds are on the order of 100 to 1,000
times more than for OC. From the farmer’s standpoint, the OP have a
more immediate lethal effect on insect pests and are much more expensive
than OC, must be applied more often, and are extremely hazardous to
use. It follows that, the OC require heavier applications to obtain
a kill but have a more lasting effect resulting in fewer applications
and lower costs, and are less hazardous in use. Economics and personal
safety are much more compelling arguments to the farmer who makes the
selection than is water quality. Thus, further regulatory activity may
be necessary in order to bring about the use of non-persistent pesticides.
I. Removal of Pesticides from Wastewaters
Treatment facilities have been developed which are highly effective
in the removal of pesticides from effluents discharged by pesticide
manufacturers. Although discharges by pesticide formulators are highly
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irregular both in content and quantity, similar treatment principles
must be applied. Treatment of irrigation drainage is equally desirable
but would involve an additional requirement, the removal of suspended
solids prior to treatment for removal of pesticides. Chlorinated hy-
drocarbons have been removed successfully from small streams and lake
outlets in Missouri and California using dams constructed in a manner
to cause the wastewater to pass through activated carbon. Efficiency
of pesticide removal has been reported to be i0 to 50 percent. Some
of the systems employ activated carbon cylinders suspended from over-
head racks such that waters must pass over and through the cylinders.
The latter system has the advantage that cylinders are quickly and
easily replaced and the efficiency approaches 60 to 70 percent.
Drip basins are a recent innovation more suited to irrigation re-
turn flows in which suspended solids would cause the activated carbon
flow-through devices to become clogged. This system depends on the
property of the newer organo-phosphorus compounds that are readily
and quickly hydrolyzed in alkaline waters. In practice, the waste-
water is diverted into a lagoon and then is charged with slaked lime,
held in suspension by aerators and maintained at a pH of 8.5 to 9.0.
After 8 to 12 hours detention, the pesticides are degraded into phos-
phorus compounds that form precipitates and settle out or are broken
down into harmless components such as methane and CO 2 . Such systems
hold promise for economic and efficient removal of organo-phosphorus
compounds from irrigation drainage.
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In the south, clay—lined ditches or channels have proven to be
highly effective in the removal of DDT and its metabolites. Although
this method holds some promise, efforts should be directed toward elimi-
nation of use of chlorinated hydrocarbon pesticides as outlined earlier.
J. Coordination of Control Measures
As is evident, no one of the control measures discussed herein can
solely be expected to eliminate the problem of pesticide pollution of
the Lower Colorado River. Very real possibilities do exist for such
control through the employment of various combinations thereof. The
scenario for successful abatement of the major pesticide pollution pro-
blems in the Lower Colorado River Basin should include application of
the Federal Water Pollution Control Act Amendments of 1972, Refuse Act
and Federal Common Law of Nuisance, efforts through appropriate State
agencies to cause effective pesticide pollution control legislation to
be enacted, the establishment of routine policing by irrigation dis-
tricts to control dumping, the implementation of requirements for deep
tile drainage of all irrigated areas, the limitation of compounds
applied to those which are non-persistent, the implementation of bio-
logical controls and physical controls that disrupt the life cycles of
the insecticide pests, and, finally, the treatment of irrigation drain-
age from the major irrigated areas.
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