The Snowflake herald., 1913-11-28
LOSS OF CANAL WATER
Too Steep Grades Are Sometimes
Responsible for Leaks.
When bitches Are Built Through
Gravelly Soils Seepage Losses
Are Naturally Heavy Unless
Measures Are Taken to
Prevent.

There is not an irrigating canal in
this country from which there is not
more or less loss of water in transit
These losses are generally spoken of
as caused by seepage and evaporation.
However, it has been demonstrated
that the evaporation losses as com
pared to those caused by seepage are
SO light that they may be disregarded
The loss by seepage unusually occurs
from the character Of the soil through
which the canals run, says the Denver
Field and Farm. When this Is finely
divided sandy loan such as occurs in
many places the losses from this
cause are generally light, but when
the canals are built through soils
which are very gravelly or perhaps
nearly pure gravel the seepage losses
are naturally very heavy unless siren
uous measures are adopted to prevent
them.
In other places much water Is lost
along parts of the canals where the
excavation has been through seamy
basaltic rock or decomposed sand
stone. Too steep grades sometimes
are responsible for much seepage.
This condition is found on some of
the smaller early bitches built through
gravelly soil. We have heard it argued
that when the water is to be conduct
ed through gravel or a porous forma
ton it should go fast, but in canals
built on this theory the velocities are
such as to prevent sitting of the chan
nels and thus actually promote seep
age. In the construction of canals
many fills are made across short gul-
lies or depressions, where to follow
the contour of the land would necessi-
tate wide detours; and frequently the
upper banks are either omitted or de-
stroyed which allows the water to
spread out over the land above the
canal and form lakes.
In cases where the fills are of con-
siderable height quite large areas of
land are sometimes flooded and below
such lakes are invariably found heavy
seepage losses, large enough often to
run in small streams away from the
canal. To prevent these losses the
upper banks of the canals have been
built up so as to prevent t'e forma-
tion of the lakes. On the canals
where the difficulty is due to gravelly
soil it has been the practice to some
extent to excavate a foot or so below
grade and then fill in with clay or fine
material, so as to form puddle. The
clay is tamped in the bottom, and then
the bottom and sides are plastered
several inches thick with a mortar
formed of the clay in plastic state.
This is then covered with layer of
gravel to prevent washing.
The results of this work are quite
satisfactory but it is difficult to find
suitable clay for the purpose and ce-
ment has to be used which is more ex-
pensive but considerably more dur
able. Some measurements have been
made on our canals to learn the extent
of seepage, but on the smaller bitches
it is almost impossible to get any re-
liable results on account of the numer-
Gus diversions which there Is no sat-
isfactory means of measuring; and II
these are shut off along stretch two
or three miles long, the extra water
will cause such rise in the canal be-
low as to be dangerous. The loss oft
en- amounts to fifty per cent. and this
is more than any business can stand.