Evening star., 1928-12-30
CONTINUED From Third Page.)

merous have been the requests for in
formation from prospective settlers on
the projected reclamation areas that
DR.. Mead has had prepared form let
ter stating 'it will be many years be-
fore irrigation water will be available
and the land to be irrigated opened to
settlement and development"
Drainage Basin Of River.
This powerful Colorado River that
duce his electricity and grow his crops
where only cactus and sagebrush now
flourish takes its birth from the head
waters Of the Green River, in the high
mountains of Wyoming. From that
point until this proverbially muddy
river empties into the Gulf of Califor-
mia, in Mexico, the Colorado courses a
distance of over 1,750 miles. The drain
age basin of the river comprises about
242,000 square miles in the United
States and 1000 square miles in Mexico
The Colorado River Board, which
made an exhaustive study of the whole
problem during the past Summer and
Fall. consisted of Mai. Gen. william
L. Sibert, chairman; Charles p. Berkey,
Robert Ridgway. In expressing its
preference for the Black Canyon site
over that at Boulder Canyon, which is
20 miles above, the board said: THE
Black Canyon site Is more accessible,
the canyon Is narrower, the gorge Is
shallower below water level. the walls
are sleeper, and a dam of the same
height here would cost less and would
have a somewhat greater reservoir ca
pacity. The rock formation is less
jointed stands up in sheer cliffs better.
exhibits fewer open fractures. is better
healed where formerly broken and Is
less pervious in mass than is the rock
of the other site. The Black Canyon
rock is not so hard to drill as that
Of Boulder Canyon, and 1t will stand
better in large tunnel excavations, with
less danger to the workmen.
There Is no doubt whatever but
that the rock formations of this site
are competent to carry safely the
heavy load and abutment thrusts con-
templated It is we'll adapted to max
ing tight seal and for opposing water
seepage and circulation under ana
around the ends of the dam. 1t in
sures successful tunneling, and, so far
safety and permanence Of the proposed
structures"
900 Feet Above River.
The board points out that at the
proposed site Of the dam the canyon
walls rise to about 900 feet above the
river and the central part Of the rock
gorge at this location is 110 to 1877
feet deep below low water. The cross
section of the gorge at the dam site
is $50 feet wide at the low-water line
and $50 feet wide at the crest OF
acre-feet of water. An acre-foot Is
the amount of water that would cover
| an acre of land to depth Of foot.
The Brobdingnagian engineering feat
contemplates the use of 3,500000 cubic
yards Of concrete-more massive than
the Great Pyramid Of Egypt. The
foundations for the dam will stretch
800 feet in length up and down the
river bed and half the concrete that
will form the dam will be below
ground. Above the dam will be a lake
| 100 miles in length and some 4 miles
wide. The cost Of the dam and res
ervoir alone is placed at $70.600,000
| The dam proper will tower aloft $50
] feet above low water, approximately
the height Of the Washington Monu-
| ment.
100000 Horsepower Possible.
The tunnels that will divert the
waters of the Colorado during the con-
struction of the dam will later be
utilized to aid in generating electricity
| and estimates point to the production
of 100000 horsepower that could be
generated at Black Canyon, with the
machinery going full blast. Further,
should additional power be desired, ex-
perts say that there are IA other dam
sites along the river that can be sum-
moned into activity as time goes on.
An auxiliary engineering problem
| to the erection of the dam is the con-
struction of railway from Las Vegas,
| Nev some 40 miles distant The Col
orado River Board has determined that
| the approach is comparatively easy to
the vicinity and not particularly difd-
cult to the site itself.
"A construction railway from Las
| Vegas would pass near available gravel
deposits, and the best quarry sites lie
Immediately adjacent to the dam site
on the same line of approach" the
| board emphasized In its report. de-
spite the ruggedness of the surrounding
| country and the depth of the gorge
| the terrain above the 1,500-foot con-
tour, where the quarries, railway yards,
shops and camps would be located, is
open, and its development into such