along the canal. The tem-
porary trashracks or por-
table pipe grids for
catching the dislodged
weeds are 8 to 15 feet
long, with a maximum width
of 8 feet, so they may be
legally hauled along high-
ways. The trashrack is
composed of two header bars
constructed from 2-inch
galvanized pipe as shown in
Figure 5, with a hole
drilled through one wall of
the headers on 5-inch cen-
ters. One-inch galvanized
pipe is inserted into the
holes drilled in each
header, then fastened with
two each 1/2- by 1/4-inch
galvanized bolts. In this
way, the l-inch pipes can
be easily replaced, if
damaged.

Figure 5 - Photo P25-D-64727D

ll


40,000 miles of canals, laterals and drains throughout the Pacific
Northwest each irrigation season for the suppression of submersed
aquatic weeds. This involves the use of approximately 800,000 gallons
in more than 10,000 applications each season. This program was carried
out during the irrigation season of 1968 without any report of injury
to man, crops, livestock or wildlife.

The xylene is applied to the water in these irrigation channels at 4

to 10 gallons per cfs over periods of 30 to 45 minutes. It is nonmis-
cible with water and consequently can be dispersed in the water only
with the help of an emulsifier. Over 20 years' experience together with
extensive research shows that the treated water can be used safely for
irrigation of crops. We estimate that 95 percent of the water containing
xylene is used for the irrigation of crops. This includes irrigation
by sprinklers, furrow, corrugation and flooding. If plants should be
covered with the water containing xylene when the concentration is
highest, there may be some burning of the plants. However, in most
cases they recover quickly. Only small seedling plants are perma-
nently injured or killed from such burning. Farmers avoid flooding

such fields.

Crop Tolerance Supported by Research

The experience described above is supported by research conducted by
the Agricultural Research Service2/ wherein typical crops were irri-
gated with water containing various concentrations of xylene” These
studies showed that reductions in yields did not occur until concen-
trations were three times the maximum used by irrigation districts.

Livestock Not Injured with Xylene

Water containing xylene is not palatable and under normal conditions
livestock will not drink water containing it. Since application is
usually made over a period of 30 minutes, animals at a given location
would be exposed to this dosage for considerably less than 1 hour.
Accordingly, it is unlikely that animals would be forced to drink the
treated water. Experiments were conducted at Utah State University
in 1952 in which 32 guinea pigs were confined on water treated with
xylene at concentrations of 400 to 800 ppm, the upper range being
greater than that applied by irrigation districts. While they drank
very little of the treated water during the first 2 days of the
trial, on the third day of confinement they drank considerable quan-
tities without visible ill effects.2/

To the extent to which guinea pigs are comparable to livestock, the
results of these tests indicate that there is no hazard to livestock
from drinking water treated with this material. In this experiment

2/USDA Circular 971, 1955.


and regrowth is rapid. This practice requires collection and removal
of large quantities of silt, broken pondweeds, and other debris loos-
ened by the chains. Naturally, this condition interrupts or prevents
water deliveries and irrigation. With the advent of sprinkler irri-
gation and the need for constant supplies of water free of debris,
the practice of chaining and dragging was gradually abandoned by many
irrigation districts and canal companies and replaced by the use of
xylene and other herbicides. This has eliminated use of 1 or more
chaining crews, each of which usually include 2 tractors, 2 pickup
trucks, and 10 to 12 men. Some of the larger districts employed 2
or 3 crews of this size. One man, 1 truck, and a tank of xylene

as shown in the cover photograph does a better job at only a fraction
of the cost of chaining, and with the use of xylene it is possible to
run the canals and laterals free of debris and with no interruption to
the water supply.

Cost of Pondweed Suppression with Xylene Versus Chaining

Submersed aquatic weeds in irrigation systems are suppressed with
xylene at only a fraction of the cost of attempted control through
mechanical methods such as chaining. The term "attempted control" is
used because none of the mechanical methods used were really effective.
At best, only a small portion of the weeds were broken loose by the
chain or disc. The remainder were only pushed into the mud on the
stream bottom where they continued to grow.

Mr. Russell Unrue, Marmager of the Bitter Root Irrigation District,
Hamilton, Montana, reports that mechanical methods of controlling pond-
weed would increase the cost of pondweed control 450 percent as com-
pared to present costs of controlling these weeds with xylene. The
following paragraph is quoted from Mr. Unrue:

"Our cost for pondweed control requiring one treatment for 1968
was $1,326 for xylene, emulsifier, labor and equipment for treat-
ing approximately 32 miles of canal, delivering 195 cfs for
8,000 acres of irrigable land. The cost for controlling the
pondweed in the same canal area by hand labor and chaining opera-
tion would be $5,500 to $6,000 and irrigation water turned off
for 15 to 20 days or more if sufficient labor is not available
at the proper time."

In a paper given at Preston, Idaho, in 1969, Mr. Carroll Wilcomb,
Civil Engineer, Bureau of Reclamation, Salt Lake City, reviewed his
and his successor's experience in the control of aquatic weeds in
canals and laterals operated by the North Side Canal Company, Jerome,
Idaho. The following is quoted from Mr. Wilcomb's paper:

"In 1966 the North Side Canal Company discontinued chain mossing
altogether in favor of chemicals. The company presently uses
around 20,000 gallons of xylene and 2,600 gallons of acrolein.


pointed out, it can be retained in water for a short period only with
the use of selected emulsifiers. Monitoring studies conducted by this
office, Bureau of Reclamation laboratories in Denver, Colorado, and
the Kennewick Irrigation District, show that 7-1/2 gallons of xylene
per cfs (approximately 555 ppm) applied to a canal at two locations
was almost completely lost to the air in 24 hours. ‘Twenty-four hours
after application, at the end of the channel 17 miles downstream, the
water contained .3 ppm xylene. Farm fields which have been irrigated
at least twice per season each year for 20 years with water contain-
ing xylene show no signs of an accumulation of xylene or any detrimen-
tal effects on crop production.

A letter dated January 17, 1969, from one of the leading oil companies
in the United States stated that xylene is not retained in the soil.
Following is a paragraph from that letter:

"Should a xylene compounded as a carrier for toxicants or soil
fumigants be injected into the soil, the manufacturer of such
products normally insists on leaving the treated area untouched
for a minimum of five to seven days. The xylene, however, will
completely evaporate in 55 minutes at 80° F. No xylene is
retained in the soil, if sufficient time for evaporation is
provided."

Xylene Is Not Toxic to Soil Bacteria

The following paragraph is quoted from page 28, USDA Circular 971,
dated 1955:

"In connection with the crop-tolerance tests, Jones3/ analyzed
soil samples taken from solvent-treated plots at Phoenix, Arizona,
and Meridian, Idaho, to determine the possible toxicity of
effluent to beneficial soil bacteria. The analyses showed that
the activity of ammonifying and nitrifying bacteria in the soil
was not affected by aromatic solvents, even at concentrations
as high as 2,400 ppm, which were introduced over 30-minute
periods. Apparently there is little danger of destroying
beneficial soil bacteria through the use of aromatic solvents
at rates which presently are recommended for aquatic weed
control."

Xylene Characteristics Similar to Gasoline

Like gasoline, cleaning solvent and aromatic solvents, xylene is
derived from petroleum oils. As much as 10 percent of "high test"
or premium gasoline is xylene. Irrigation districts, canal compa-
nies, and governmental agencies handle xylene much in the same
manner as they do gasoline.

3/Unpublished data from experiments conducted by L. W. Jones,
Bacterialogical Department, Utah Agricultural Experimental Station.


the guinea pigs were confined to the treated water, whereas under nor-
mal conditions, livestock would have access to treated water for a
matter of only minutes two or three times during an irrigation season.

The June 1957 issue of Ilygienic Guide Series states that: ''No fatal
cases from inhalation of vapor consisting wholly or chiefly of xylene

have been reported."

Xylene Suppresses but Will Not kill Pondweeds

Photograph 1 - P222-D-50462NA

Photograph 2 - P222-D-S0461NA

Because xylene affects
only those portions of
the pondweeds above
ground, control is tem-
porary. It is necessary
to repeat treatment when
new growth of the weeds
begins to fill the chan-
nels. Two or more appli-
cations are required
during each growing sea-
son. Canals and laterals
which have been treated
for more than 20 years
show no reduction in num-
ber or size of pondweeds.
Pondweeds have clogged
this lateral as shown in
Photograph 1. However,
through the use of xylene
the dense growth shown in
the photograph could have
been prevented. Sub-
mersed aquatic weeds are
rooted, or attached, to
the bottom of canals,
laterals, or drains. They
grow freely in water,
buoyed by air cells in the
leaves and stems. ‘The
Giant Sago pondweed, shown
in Photograph 2, is 12 to
15 feet in length.

Xylene Does Not Remain
in Water or Soil

Xylene, like gasoline and
other related products,
is volatile and evaporates
when exposed to air. As


Photograph 3 - P3-100-147

Photograph 4 - P3-100-148

Chaining (Dragging) Canals and Laterals

Since the beginning of irrigation in the West, men have tried and

under some conditions must continue to remove pondweeds from canals
and laterals by dragging these channels with chains, discs, binder
wheels and other instruments. Although this method may be repeated
every 10 to 15 days throughout the irrigation season, it generally
is very ineffective. Only a fraction of the weeds are broken loose


Department of the Interior, Bureau of Reclamation

IRRIGATION OPERATION AND MAINTENANCE

BULLETIN NO. 69
July, August, September 1969
LST viPY D io
0 NOT R ined —
>
tad

(ast coPY - DO NOT REMOVE

In This Issue:

The Use of Xylene for the Suppression of Submersed
Aquatic Weeds in Canals and Laterals

Weed Control and Removal Equipment

Hydraulically Operated Spray Rig for Weed Control
Mechanical Trashrack

Pumping Plant Trashrack
Seraper for Cleaning Canals

Herbicide Monitoring Study in Irrigation Systems


WEED CONTROL AND REMOVAL EQUIPMENT1/

Gang Discs and Chain

Gang discs, dragging a loop ot heavy-duty anchor chain, have been
found highly successful where mechanical methods are desirable in
dislodging aquatic weeds in the Salt River Project canal system. The
discs tear up the soil and loosen weeds. Then the chain drags out
weeds by the roots and smooths the disced canal bottom.

Two medium duty tractors, one on each side of the canal, pull the
equipment upstream and down along the canal bottom to tear out the
equatic plants. Figure 1 below shows the gang of heavy discs on the
canal bank prior to beginning a weed removal job. Figure 2 on the
following page shows how the water is churned up by the discs and
anchor chain during the weed removal operation. Up to five or six
passes are made in a single treatment.

Figure 1 - Photo P25-D-64723

1/This article was written by Mr. W. L. Simser, Superintendent,
Construction and Maintenance and Agriculture, Salt River Project,
Phoenix, Arizona.


Total annual cost in 1968, including material, equipment, labor
and overhead was about $25,000 or less than half our mechanical
operation in 1955. The cost saving is even greater because of
the substantial increase in operating costs since that time."
Through pool purchasing by a number of projects in an area, the cost
of xylene and emulsifier per gallon used in the suppression of pond-
weeds has been reduced 15 percent in the past 10 years. Accordingly,

the cost of pondweed suppression with xylene as compared with the cost
of chaining if practiced at this time would be much less.

ee RR

Driving attitudes can contribute to accidents. The following list
is excerpted from the National Safety Newsletter as a reminder to
drivers. Keep your calm and don't let these attitudes develop:
The ''me-first'' attitude. Shows lack of concern for others.
The self-important. Rules apply to the other fellow.
The over-confident. I know it all. I never had an accident.
The "live dangerously" type. It can't happen to me.
The fatalist. You go when your number is up.
The hostile type. Constantly angry towards others.
The inferiority type. Please don't push me around!
The competitor. Must always be ahead of the other fellow.
The "tired of living.'' A need of self-destruction.
The exhibitionist. A show-off.
The sadist. Derives pleasure from hurting or threatening.
The self-righteous. It is always the other fellow's fault.

It is easy to see that the attitude of one person could very well
determine his classification as a good driver.

tee RE


Circular No. 58, "Herbicides (How Poisonous are They?) ,'' published by
the University of Idaho in 1967, compares the toxicity of various
herbicides when injested by small animals. In this comparison the
herbicides are given numerical ratings: 1 - extremely toxic, 2 -
very toxic, 3 - moderately toxic, and 4 - almost non-toxic. Aromatic
solvents (xylene) and gasoline are both rated No. 3. Kerosene is
rated No. 2 to 3.

Canals and Laterals Do Not Support Fisheries

The small number of fish found in these channels are there by acci-
dent. These channels carry water only 6 to 7 months each year
during the growing season, being dry for the other 5 to 6 months.
Consequently these waters cannot be used as fisheries. Fish that do
enter the irrigation systems are doomed to perish at the end of the
irrigation season.

Xylene Is Toxic to Fish. Water Containing Xylene Is Not Permitted
to Enter Natural Streams

Xylene is toxic to fish; consequently, irrigation water containing
xylene is not permitted to enter natural streams and rivers. As
pointed out previously, water which has been treated with xylene is
used for irrigation of crops and under most conditions any of the
treated water remaining at the bottom of the fields after irrigation
has lost the xylene to the air. In the few cases where xylene may
remain in the water after irrigation, the water is wasted into hold-
ing ponds, or onto noncultivated areas. At the end boundary of some
districts, waste water containing xylene can be spilled over drops
causing extreme agitation and loss of xylene into the air.

Controlling Pondweed by Drying

During the period of early settlement in the West and until about
1930, water for irrigation was plentiful and the methods of irriga-
tion and the type of crops grown tolerated interruptions in water
deliveries. Drying of ditches 4 to 5 days for the control of pond-
weed was a common practice. The need for maintaining uniform moisture
conditions associated with row crop farming and a greater demand for
water have made the practice of drying unacceptable to most farmers.

Hand Mowing Pondweeds

During the period preceding 1950, it was not uncommon to find crews
of three to six men engaged in cutting pondweeds in the shallower
laterals and canals with scythes, as shown in Photograph 3 on the
next page. The cut weeds, also shown on the following page in
Photograph 4, were collected on trashracks and lifted from the
streams. This very costly practice was repeated every 8 to 12 days
depending on the severity of the weed infestation, water tempera-
tures, and the demand for water.


THE USE OF XYLENE FOR THE SUPPRESSION OF
SUBMERSED AQUATIC WEEDS IN CANALS AND LATERALS1/

Over a period of more than 20 years the use of xylene has made it pos-
sible for some irrigation districts and canal companies in the Pacific
Northwest to deliver adequate quantities of clean water to all farms on
their projects. This was not the case when the districts relied on
chaining and other methods to control these weeds. This program has been
carried out without injury to man, livestock or crops. Only in rare
cases of accidental spilling of treated water into natural streams has
there been damage to fish.

While the greatest benefit from the use of this product has been in
the districts being able to give uninterrupted service of adequate
quantities of clean water to all farms, the saving in cost to the
water users has been substantial.

Xylene Is Registered and Approved for Use in the Suppression of Pond-
weeds in Irrigation Systems

All herbicides used for the control of aquatic and terrestrial weeds
must be registered by the Pesticide Regulation Division, Agricultural
Research Service, U.S. Department of Agriculture. This registration

of a product requires the approval of the Pure Food and Drug Adminis-
tration, Sports Fisheries and Wildlife, National Pesticide Review Board,
and others. The Pesticide Registration Committee is staffed with per-
sons having broad experience and training in determining hazards con-
nected with the use of chemicals.

As a prerequisite for registration of a particular herbicide, informa-
tion and research data must be provided to convince the regulatory
government agencies that the use made of the herbicide will not be
injurious to man, crops, livestock, wildlife and our environment, and
yet be effective on the target organism. Xylene is registered for use
in the control of pondweeds in irrigation systems. This registration
carries the approval of the departments and agencies mentioned above.
Because of the broad use of xylene throughout the world as a pesticide
solvent and carrier and because of its safe use on crops, we anticipate
that any further consideration by regulatory agencies of its use in
irrigation water will place it in an exempt status as far as tolerances
are concerned.

Crops Not Injured with Xylene

Irrigation districts, canal companies, county and state governments,
Indian Service and the Bureau of Reclamation apply xylene to more than

1/This article was reprinted from a report prepared by Mr. W. Dean Boyle,
Regional Agronomist, Region 1, U.S. Bureau of Reclamation, Boise,
Idaho, in response to an inquiry concerning the use of this product.


A mobile crane, as shown in Figure 6 below, is used to set the grids in
place against various canal structures or bridges. They are positioned
in the water at an approximate 45-degree angle, as shown in Figure 7
Note that the grid is being set into the notches or scallops on the

lip of the structure. This holds the grid snugly and resists shifting
during the raking operation.

Figure 6
Photo
P25-D-64728D

Figure 7
Photo
P25-D-64729

12


growth. This latter procedure requires operating skill to avoid damage
to the grids.

Transportation of Equipment

A flatbed truck is used to haul the discs, chains, and grids from
station to station on the canals. The discs, chains, and bucket are
carried on the bed, while the grids are cradled in a rack built over
the bed. Figure 10 below shows a typical flatbed truck used for this
purpose. The equipment is offloaded by the same mobile crane which
is used to position and clean the grids.

Figure 10 - Photo P25-D-64732D

Costs

The described process, which costs about $170 per mile, is repeated
from station to station on the canals during the growing season to
maintain full canal capacity.

Anyone seeking additional information should contact the writer at
the Salt River Project, Post Office Box 1980, Phoenix, Arizona 85001.

a ed

14


IRRIGATION OPERATION AND MAINTENANCE
BULLETIN No. 69

July, August, September 1969

INTRODUCTION

This issue of the Bulletin is devoted exclusively to weed control meth-
ods and equipment being used on some irrigation projects in the west-
ern part of the United States. The use of xylene for the suppression
of submersed aquatic weeds in canals and laterals is the subject of an
article starting on page 1. Included is a comparison of the cost of
pondweed suppression with xylene and the chaining methods.

As a follow-up article to that appearing in Bulletin No. 64 on "Eval-
uation of Cost and Effecitveness of Canal and Lateral Aquatic Weed
Control," the second article in this issue of the Bulletin beginning
on page 9, describes the various types of equipment used for weed
removal from Salt River Project canals in Arizona. Removal of pond-
weeds by this method is a necessary part of their operation.

Beginning on page 15, an article by Mr. R. F. Carter, of the Imperial
Irrigation District, Imperial, California, describes the hydraulic
spraying equipment used by the District that is so necessary in this
particular environment on the project. The article describes a unit
developed and field tested during the 1967 fall spraying season.

A mechanical trashrack developed and used on the Northport Canal, North
Platte Project, Northport, Nebraska, is described and illustrated in an
article that begins on page 19.

To prevent frequent shutdowns at the Burbank No. 3 Pumping Plant on
the Columbia Basin Project, Ephrata, Washington, a supplemental trash-
rack was installed. The supplemental rack was built because of a heavy
concentration of debris. This problem and the new trashrack are
described in a short article on page 23.

On page 24, there is described a scraper for cleaning sediment and
algae from canals that was developed and fabricated by the Metropolitan
Water District of Los Angeles, California.

The purpose of a cooperative study to determine the fate of various
herbicides in irrigation water is the subject of an article starting
on page 25. This study is the result of routine herbicide applications
made on irrigation systems.


The Irrigation Operation and Maintenance bulletin is published quar-
terly, for the benefit of Irrigation project people. Its principal
purpose is to serve as a medium of exchanging operation and mainte-
nance information. It is hoped that the reports herein concerning
labor-saving devices and less costly equipment and procedures, devel-
oped by resourceful project people, will result in improved efficiency
and reduced costs of the systems for those operators adapting these
ideas to their needs.

To assure proper recognition of those individuals whose suggestions
are published in the bulletins, the suggestion number as well as the
person's name is given. All Bureau offices are reminded to notify
their Suggestions Award Committee when a suggestion is adopted.

wk KR

Division of Irrigation Operations
Office of Chief Engineer
Denver, Colorado 80225

COVER PHOTOGRAPH:

Watermaster for the Frenchtown
Irrigation District, Montana,
applying xylene to the Frenchtown
canal for the control of pondweed
and algae. Photo P222-D-50460NA



Figure 2 - Photo P25-D-64724D

From S to 11 discs are used, depending upon the width of the canal. A
single disc unit is shown in Figure 3 below. The discs cost about $350
per unit and last about 3 seasons, with normal replacement and repair
of various parts.

The heavy-duty anchor chain
which the project obtained
from a salvage yard some
years ago, is about 90 feet
long, with links weighing
90 pounds each. As the
chain wears, the project
machine shop rebuilds the
metal on each link to retain
the necessary weight. The
chain also is equipped with
three large swivels to per-
mit it to roll without
twisting the cable leads.

Portable Trashracks

The dislodged growth floats
downstream and is trapped
by barriers of pipe grids,
Figure 4, temporarily set
up at various structures

Figure 3 - Photo P25-D-64725D

10


Figure 9 - Photo P25-D-64731D

13

Figure 8, at left is a view
of the grid set into the
scallops on the lip of the
structure, and also it
shows workmen securing the
grid to the structure chain.
Individual 1l-inch-diameter
pipes are laid in a similar
manner near the sides of
the canal as shown previ-
ously in Figure 4, to fill
in the gaps created by the
slope of the canal banks.
Average cost of the grids
is $150 each. They last
about two seasons, with
normal maintenance.

Weed Bucket

As the dislodged growth
floats downstream and
begins to lodge against the
grids, it is removed by the
bucket shown in Figure 9,
that was designed and built
for this purpose by the
project. The bucket is
lowered in such a position
to permit the bucket teeth
to pass between the grid
pipes. It is then raised,
removing the accumulated
growth to the canal bank
for partial drying before
the weeds are hauled away.

If the crane can be set up
directly behind the grids,
they can be cleaned by drop-
ping the bucket upstream
and pulling it up against
them. If it is necessary
to work from the side, the
bucket has to be lowered
carefully on the grids and
then pulled upstream and to
the side for removal of the