Nearly a year was spent in investigating bed rock conditions before the
foundation was placed. Enormous boulders eighty feet in thickness were
discovered in the bed of the stream; the removal of these, owing to the
narrowness and depth of the canyon, proved expensive and difficult.
Before any work was undertaken in clearing the channel of obstructions,
the river was passed around the dam site by means of a tunnel. During
the early period of construction the laborers were taken to and from
their work, hundreds of feet below the camp, by means of baskets, and
skips were suspended on cable ways across the gorge. Sudden floods,
extreme cold weather, short seasons, and other unfavorable conditions
greatly retarded progress.
The dam is a wedge of concrete, with curve up stream, 328 feet in
height, and 200 feet long on top. It has restored the lake of olden
times, and this beautiful body of water is now one of the attractions
of the trip to the Park. The stored water will be utilized for the
irrigation of 150,000 acres of land on the mesa (a high, broad, flat
table-land) below Cody. This region until 1907 was a worthless and
uninhabited desert. Today it is occupied by more than 700 farm families
and three growing towns.
_Conquering the American Nile_
[Illustration: LAGUNA DAM, ARIZONA-CALIFORNIA
Length, 4781 feet; 19 feet high. Division Gates, 17×33 feet, are the
largest in the world]
The delta of the Colorado River, in Arizona and California, is often
described as America’s Valley of the Nile. In climate, soil and
agricultural conditions it is singularly like the great valley of
Egypt. The conquest of this turbulent river of the West was a splendid
achievement. The engineering features of the Yuma project, in Arizona
and California, are in many respects original. The control of the
stream called for a long diversion dam and more than 100 miles of
strong levees. The dam is nearly a mile long, nineteen feet high,
and 267 feet wide on the bottom. Its type is similar to that of the
barrages of the English engineers in India. Laid on a foundation of
shifting sand and silt, it is held in place by its enormous weight,
600,000 tons. Owing to the quantities of silt carried by this stream,
the dam is provided with a large settling basin, sluiceway and gates,
by which comparatively clear water is turned into the canals. The main
canal system extends for twelve miles on the California side. Just
opposite the city of Yuma, Arizona, the entire volume, 1,000 cubic feet
per second, is dropped in a siphon 1,000 feet long and carried under
the river to the Arizona side. Here are 90,000 acres of valley and mesa
land, and more than half of the area is being developed intensively.
The soil is of great depth and extremely fertile, and the climate is
adapted to the growing of a wide variety of crops. The mesa lands which
are to be opened later are described as frostless, and especially
adapted to growing citrus and other semi-tropic crops.
_The Pathfinder Dam_
[Illustration: GRAND RIVER, ROLLER-TOP DIVISION DAM, COLORADO