The L'Anse sentinel. (L'Anse, L.S., Mich.) 18??-current, 1891-06-06
GREAT SwOREOF WATER.
THE GREATEST ARTIFICIAL IRRI-
CATION RESERVOIR.
1t Is Held by the Great Bear valley River
Dam In San Bcrnardino County,
In CalIfornla--Fuiiy Two
Miles Wide In Places.

~
in America and perhaps in the world,
is that controlled by the Bear valley
dam in the mountains OF San Bernar-
dino county, California. 1t affords a
demonstration of hitherto INFESTED
principal in engineering in relation to
masonry dams, and at the same time
Is an illustration OF the preservation of
the maximum amount OF water at the
minimum OF cost. Natural advantage
OF location had great deal to do with
this, it is true, but boldness in con-
struction is also entitled to much of
the credit. The immediate cause of
construction OF the Bear valley river
reservoir was found in the rapid in
crease OF population in that part OF the
state in the few years prior to 1880.
and the corresponding increase in the
demand for water for irrigation.
This valley is an extensive basin ten
or twelve miles long and of varying
width, lying at an elevation OF about
$500 feet above sea level. The sur
face was remarkably level consider
ing the generally rugged character Of
the country, and examination suggests
the idea that at some remote period the
valley was occupied by lake, which
had its outlet down dry and rocky
water course at the eastern extremity
to the level of the Colorado desert.
The valley is fully two miles wide in
place< and at the western extremity
narrows 70 rocky gorge between
lofty cliffs down which flows the water
of Bear creek to its juncture with the
Santa Ana.
This valley attracted the attention of
+. 4. Brown, young graduate of
Yale, who came to California in 1876
to practice his profession as civil engi-
neer He was engaged in the reclama-
ton OF large tract of apparently
desert land in the eastern portion of
the San Bernardino valley, and it
became necessary to obtain much
larger water supply than was available
in the streams of that locality. 1t was
found that dam sixty feet in height
would form water plane six miles in
length and covering some 2 800 acres.
Work on the dam was commenced in
1888, and owing to the difficulties in
the way of getting cement and other
material over the mountains it was
decided to adopt novel idea in dam
construction. Instead of erecting an.
immense mass of masonry. which
should confine the water by virtue OF
its gravity alone, it was decided to
adopt the arch principle. Since the
vertical arck will sustain immensely
more weight tGAn fiat sYface, it was
reasoned that an arch laid horizontally
upon the ground would withstand the
pressure Of a much greater amount of
water than wall OF the same size laid
in straight line. Simple as this pro-
position seems, it has been fiercely
combated by prominent engineers. In
defiance of opinion against the idea.
Engineer Brown went ahead with his
work. He planned wall twenty feet
thick at the base and three feet thick
ut the crown. At the foundation it
was but sixty to seventy feet wide,
rapidly increasing with the slope of
the bank. until at the coping 1t Is 800
feet from shore to shore. The radius
OF the arch is 335 feet, and the extreme
height Of the wall is sixty-four feot.
The dam was success in every way,
and 1t has been extensively copied in
more recent structures. Although the
expense OF transportation Of supplies
was great, it was finished at a cost of
&75, 900. The result was marvellous.