Imperial Valley press., 1921-10-13
IS
READY MADE
BY MOTHER
NATURE
Granite Cliffs Tower 800 TO
1900 Feet High in Gorge;
200 Feet Wide at Base. -

Continuing his story of the recent
trip made to Boulder Canyon, E e.
Hollingworth, a Los Angeles news
writer has this to say of the proposed
dam:
The proposed reclamation, irriga-
tion and power dam at Boulder can
yon on the Colorado river will rise
600 feet above water level and extend
$50 feet under the rivers surface to
rest on bed rock.
The site is in natural gorge cX-
tending for about three miles or a
little less, the river winding, with
sharp turns at frequent intervals, be-
tween towering cliffs of solid granite
which rise to the height of 800 to
1900 feet.
The site for the dam could not have
been more ideal if nature hNd planned
it for the irentical purpose. So Tor
chilly does this fact impress itself on
the beholder that one of the engi-
leers who recently made several
days visit to Boulder canyon was
moved to eXclaim:
'The Almighty must have made
this place on purpose for power
dam; and | can imagine Him sitting
and looking down on this great South
west and saying, What fools these
people are that they do not use it,, "
And it was not said in jesting or
irreverent manner either.
In the gorge. which is so narrow
that the base of the dam will be but
200 feet wide, the cliffs are solid
granite for about 800 feet, being top
ped with a basaltic formation not SO
hard as the base.
The water will not rise to this lava
rock, however, and the everlasting
granite will form bar to the tre-
mendous volume of water to lie I'M
pounded, which will not be subject
to waste or seepage.
At the top of the dam will be but
1000 feet wide, and the natural crew
ices in the rock into which the wings
of the mighty obstruction will ex-
tend will furnish natural leverage
which will only jam it tighter into
place.
Two forms of dam are under con-
deration-concretc and rock fill
The concrete dam is under most con-
ditions the better of the two, al
though much more costly to con-
struct. In many other power devel-
opments scattered throughout the
country the writer has seen it in sue
cessful use, especially where there
is flat or low country on one or both
sides.
| Here is Boulder canyon. however,
conditions are so vastly different
from most other kindred projects that
many engineers favor the rock fill
dam. Here is granite already at a
sufficient elevation above the chap
mel, which can be blasted down into
the stream below and find place by
sinking into the lighter sand, aided
by the turbulent floods of two or
three seasons.
In close proximity also are gravel
beds, necessity in this latter type
of dam, and this simplifies the pro-
posal should the rock fill construction
be decided upon.
The top of the dam will be 1919
feet above sea level, uniting hills
which are from 1900 to 1900 feet
above sea level. The 1264-foot mark
is the highest. 1t is expected the
water would ever rise, this being
based on statistics of the last %
years, since the river came under
close observation. For safety. how
ever, the additional height will be
added, which will amply safeguard
the lands reclaimed further down the
Colorado under any conceivable cir
cumstances which might arise.
The spillway will be constructed al
the 1264-foot mark, capable of dis.
charging $4,000 to $4,000 cubic feet
per second during flood neriods. This
it is estimated, will be all that is re-