WSPC00104

• File Number: 8408
• Description: River Basin General Correspondence
• Date: 1/1/3000
• Title: Fourteenth Annual Report, Pathfinder Irrigation District
• Water Supply Pro - Doc Type: Annual Report

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LOSS

SEEPAGE & DRAINAGE

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The percent of loss in canals and laterals is greater during the
dry years than during wet years,

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When the canals and laterals are not operated to capacity the percent
of loss increase out of all proportion to the difference between the normal
flow and the reduced flow,

The total Project loss for the 1939 season was 261,789 acre feet.
This includes loss in canals, laterals and reservoirs located on the project,
This equals 57% of all water diverted into the head of the canal, and is 6%
greater than that of the 1938 season.

The percent of loes in 1934 was 66%, tlt..t was the year that water
was turned into and out of the canal several times during the season. Siilee
that time, it has been as low as 51% and ~~ hi~h as 61%.

The greatest loss in the main canal seems to be in those se~tions
where the canal passes through brule clay,

'I

The programe of graveling inside slopes of canal banks is for the
dual purpose of holding the alignment and trapping the silt in among the
gravel, to reduce the seepage, It has done some good in regards to the seep-
age problem but the loss ia still very high and some type of lining seems to
be the only cure.

A method of applying tar, to, cotton fabric furnished b.y the surplus
commodities corporation, was tried in the low line canal. It cured the seep-
age at that point ~ut it is only a temporary measure as the fabric has begun
to rot and the seams to open.

The percent of loss is about equally divided between the Cansls,and
laterals but the loss in acre feet is almost twice as much in the canals as
in the laterals,

If the loss in laterals alone was prevented about 80,000 acre feet
of additional water could have been delivered to the land, Th~ major portion
of this can be prevented by concrete lining.

The members of
of laterals to date and
relocation of laterals,
to be lined,

the C. C. C. Camps have concreted lined 27 miles
about 6 miles of laterals have been elimited py the
But there are still about 570 miles of laterals yet

It was thought best to concentr.te the efforts of the C. C. C. on
later~ls because the allotment of those camps was not sufficient to undertake
a job ~s large as the Main Canal,

The area of seeped land varies ~th the amouut of irrigation lmter
a'""Uahle and the :alIJotmt of rAin raIl.

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