The Ronan pioneer. [volume] (Ronan, Mont.) 1910-1970, 1916-11-17
Hardin Irrigationists Propose to Harness
Big Horn, Develop Power, Reclaim Land
Cost of Project Twelve Million Dollars

The construction of dam $50 feet
high. which would be the highest in
the world, in the canyon of the Bi"
Horn river in southern Montana and
the laying of railroad 6S miles long
from Custer through Hardin to the
foot of the canyon with spurs to the
base and top of the dam are projected
by the Big Horn Canyon Irrigation &
Power company with headquarters at
Hardin. This dam would impound
the flood waters of the third largest
river in the state in the depths of one
one the most awe-inspiring chasms on
the continent for utilization in irri-
cation and to furnish hydro-electric
power for the transcontinental rail-
roads and for manufacture, particu-
larly for the extraction of nitrogen
from the air
For more than two years the engin-
GERS have been engaged in the surveys
and in the preparation of maps to
meet the requirements OF the depart
ment Of the interior at Washington.
Surveyors Obliged to Cut
Way Along Cliffs.
This work has been hampercd bv
the almost inaccessible nature of the
canyon. Until the appearance of the
surveyors few had accomplished the
feat of traversing the canyon and
several had been drowned in the at
tempt to run the rapids. The most
difficult problem of the survey was
solved by the cutting of trail, %
miles in length, from the lower end
of the canyon to a point opposite the
mouth of a tributary known as Dry
Head canyon. This path follows the
east slope or wall of the canyon at
heights varying from so to 1000 feet
above the river. At many points it
had to be blasted out Of the face of
precipitous rocks, wide enough to per-
init the passage of pack animals. By
this trail portage was provided be-
yond the most dangerous of the rapids
whence boats could be used safely.
Rocky Walls Rise 900 Feet
Above Proposed Dam Site.
The site of the dam was selected
at point five-eighths of a mile above
| the mouth of the canyon. At this
point the river flows between precip-
itious cliffs of limestone rock, which
rise 900 feet above it.
At it's base, measured at high
water mark, the canyon is but 16O feet
wide The conformation is described
as strikingly similar on the two sides
and the top of the dam will reach a
point half way up the higher tiers of
cliffs, the distance between which is
1150 feet.
Hard, flinty bedrock, free from ere
vices, was found at depth Of only
five feet under the channel. The side
walls of the canyon also, beneath the
point of weathering action were found
to be of hard rock, without seams.
The dam would be built of solid
rubble concrete. 1t would be $50 feet
high from the bottom of the ,founda-
ton, 20 feet into the rock under the
channel, and, carried to firm rock in
the slopes of the canyon, would be
800 feet long on top. The thickness
at the bottom would be 1928 feet. 1t
is estimated that !, 100000 cubic yards
of concrete would be required.
Tunnel for Diverting Flow
To Be 800 Feet Long.
The tunnel for diverting the flow of
the river while the work on the dam is
in progress will be 800 feet long. Its
length would be shortened by a con-
venient bend in the canyon just above
the dam site. The spillway will con-
sist Of tunnel 2,4O0 feet through SOL
id rock.
1t is pointed out that from an en-
gineering standpoint the construction
problems are simple and that the adj
vantages in the ratio of length to
height and in depth of foundation
compare favorably with corresponding
features of other notable structures
Of the kind. The Arrow Rock dam,
near Boise, Idaho, is 35l feet high,
the highest in the world yet con-
structed, and 1,O75 feet long and the
foundation extends so feet below the
river bed. The Sun River dam i'll
Montana is 800 feet high and 9S9 feet
long. The Shoshone dam, in Wvo-
ming, is 1928 feet high and 200 feet
long on the crest, but the depth of
excavation for the foundation was So
feet. The Roosevelt dam in Arizona
is $50 feet high and 1,125 feet long
on top.
Reservoir Would Extend
Above Canyons Head.
The reservoir will extend the entire
length Of the canyon above the dam
and seven miles beyond. The storage
capacity, to level of 435 feet above
low water, is computed at 36,143,749,
$50 cubic feet. Half the annual flow