The story of the Colorado River Dams starts in pr-historic times with Lake Cahuilla. There is geological evidence of the lake being present as far back as 26,000 years ago.
There is also evidence of human activity along the shore for at least the past 3,000 years. This can be seen as diversion dams and fish traps.
It would take up to 20 years to fill the lake once the Colorado River breached and estimated 60 years to empty after the river returned to it's channel.
It is also estimated that the lake filled and receded at least five times between 700 and 1700 CE. Rich soil was deposited each time.
By the mid 1800s the area now known as Imperial Valley had dried enough to allow crossing in foot.
Lt. Col. W. H. Emory of the United States Army crossed the area in 1846 with an expedition to San
Diego. Capt. A. R. Johnson, an officer in Col. Emory’s expedition, was probably the first to recognize that
the Valley was once covered with water, for he wrote: “At no distant day, this place which is now a dry
desert was once a permanent lake.” But he made no reference to the fact that the area was below the level
of the sea. (IID- First 40 years, pg4)Dr. W. P. Blake
In 1853, four expeditions which had been authorized by the Congress were sent out to find a practical
route for a railroad between the Mississippi River and the Pacific Ocean. One of these expeditions, in the
charge of Lt. R. S. Williamson of the U. S. Topographical Engineers, was assigned the exploration of a
southern route and discovered San Gorgonio Pass, a natural gateway from the coast of Southern California
into the interior.
It was in the course of this survey that Dr. W. P. Blake, a geologist attached to the Williamson party,
made the first scientific examinations of and gave the name to the Colorado River Desert. His report is
included in Volume V. Pacific Railway Reports. He noted that what was then the dry bed of Salton Sea and
the surrounding area were below sea level, thus presenting the possibility of irrigating Imperial Valley from
the Colorado River. He also recognized the fertility of the soil of the area and states in the report:
“From the preceding facts it becomes evident that the alluvial soil of the desert is capable of sustaining
a vigorous vegetation. The only apparent reason for its sterility is the absence of water, for wherever
it is kept moist vegetation springs up.
“If a supply of water could be obtained for irrigation, it is probable that the greater part or the desert
could be made to yield crops of almost any kind. During the seasons of high water, or of the overflow
of the Colorado, there would be little difficulty in irrigating large areas in the vicinity of New River
and the Lagoons.
“By deepening the channel of New River. or cutting a canal so low that the water of the Colorado
would enter at all seasons of the year, a constant supply could be furnished to the interior portion of
the desert. It is indeed a serious question whether a canal would not cause the overflow of a vast
surface and refill, to a certain extent, the dry valley of the Ancient Lake. This is possible and would
result provided no change of level has taken place since the water dried up.” (IID- First 40 years, pg4)In 1892, Mr. C. R. Rockwood, an engineer, was brought in by the Arizona and Sonora Land and Irrigation Company to investigate the feasibility of irrigating land in Sonora, Mexico from the Colorado River.
Excavation of the intake canal at Hanlon Heading for Chaffey Gate Near present Rockwood Heading
Chaffey Gate
Five hundred feet north of the international boundary line in California and downstream from the present Hanlon Heading structure
The first delivery of water in the United States Delivery was made as far as Calexico through the Boundary Canal
United States Reclamation Service
In accordance with the Reclamation Act, Secretary of the Interior Ethan Allen Hitchcock established the U.S. Reclamation Service within the U.S. Geological Survey (USGS).
note "Sources"
- ==Sources==
- https://sandiegohistory.org/journal/1975/january/imperialimages/