Imperial Valley press., 1938-02-21
DISTRICT
REPORT
CONTINUED
(l6th InSIa1ImtnII
NEW WORKS

On December l, 1882 a contract
was executed between the United
States and Imperial Irrigation Dis
trict for the construction OF the
All-American canal project. This
was undertaken to maintain control
of the water used on lands in the
United States and to provide I'M
perial Irrigation District with wa
ter from which substantially all
of the silt and sand are removed.
The All American canal will head
at Imperial dam on Colorado river
above Yuma, where deSilting works
are being provided. The silt trap
ped i'm the settling basins will be
removed by mechanical means, and
will then be washed out into the
channel of the river below Imperial
dam. 1t is hoped that it can be
kept moving down the river by the
releases of relatively small amounts
of water, but the disposal of this
silt may develop into a major prob
lem, and no estimate can now be
made of the potential costs which
may arise both directly and indi-
rectly.
For about ten mics below Impe-
rial dam the canal will follow along
the side of Colorado river where
seepage will be of no material i'm
portance. In the stretch of canal,
however, from Laguna dam to Pilot
Knob All American canal will be
close to and we'll above the Cali
fornia unit of the Federal Reclaim
alton Project now served from La
guna dam Here the canal has been
built to carry $4,000 cubic feet per
second to a point where water will
be taken off for the Yuma project,
and from there to Pilot Knob the
capacity will be 1900 cubic feet
per second. Even a very small per-
centage of loss by seepage out of
the canal will constitute a large
addition to the groundWater under
the irrigated area. Serious damage
to this part Of the Yuma project
may thus result, but no estimate
can now be made of the extent Of
such potential damage.
West of Pilot Knob, All American
canal follows along the Interna-
tional boundary to the sand dunes,
there turns northWesterly through
the lowest available pass in the
dunes, and then cuts back again to
a route along the boundary. Thru
the dunes the canal has been con-
Structed to a capacity of 10000
CTS. and is here 1870 feet wide on
the bottom and roughly 300 feet
wide at the top of the cut, which
is about so feet in depth. The sand
hills bordering the pass through
which the canal is located are more
than 100 feet higher in some places.
Material disposed from the cut
forms a ridge along each side as
deep as the cut, SO that the water
will flow through a channel almost
100 feet below the level of the
surrounding ground The cost OF
the shifting sands has been the
subject of much conjecture, and
estimates have ranged from nom
inal amounts to hundreds of thou
sands of dollars per year. Neither
extreme is probably correct, and
the answer must lie in the future
A little beyond the sands hills
the proposed Coacnella Branch will
take off. This canal will eventual
ly serve lands on the East Impe-
rial Mesa and in the Coachella
Valley northwest of the Salton Sea.
It's capacity is to be about 2500
CTS. so that the All American can
al west of this division point is
being built to carry roughly 7500
CTS. Across Imperial Valley the
size of the All American is gradu-
ally reduced at each point of de-
livery into the existing canals OF
Imperial Irrigation district. About
1000 CTS. are 20 be carried around
the west side of Imperial Valley for
eventual use on the West Imperial
Mesa.
Imperial dam is now almost COM
pleted and it is planned to prime
the All American canal during 1888
as far down as Pilot Knob. Within
the next year, the Bureau of Re-
clamation expects to make deliver
les into the canals of Imperial Irri-
cation district. The actual cost of
the work to Sept 80, 1897 was $23,-
All, ,486, including the amount then
contracted. The cost to complete
the project is not known, but it is
estimated that the Imperial lrriga-
ton District will be called upon to
repay at least $25,000.000, and pos
sibly $5,000,0O0 more.