||Hoover Dam and Flood Control|
Unbelievable Man-Made Disaster That Almost Could
Not Be Undone - What is was like before
Hoover Dam ...
In the distant past, the Gulf of California, which the Colorado river flows into, extended 150 miles further inland from its present shore. There it formed a large bay that was 50 miles wide. Each year the river deposited over 140,000 acre feet of silt on the rivers delta. This is enough to cover 214 square miles in 1 foot of soil. Eventually these accumulated deposits grew so thick as to seal off the upper portion of the gulf. Cut off from the river, the water that remained formed a huge shallow lake. When the Colorado River flooded in the spring, its waters would spill into this lake. Over time, flooding, local run-off and evaporation made this a salt water lake.
The area evolved into a geological anomaly. It became a huge 2000 square mile desert, the Colorado Desert and the lake was known as the Salton Sink. At its lowest point, it was 300 feet below sea level.
In the early 1850's, a former New Orleans physician, Oliver Wozencroft, conceived the idea of cutting a channel from the Colorado river to the Colorado Desert. Since the Colorado River flowed at a higher elevation than the desert, it would be simple to bring water to the desert. Gravity would do most of the work. Bringing water to the desert would allow for irrigation and turn the area into valuable farmland.
In 1859, the California legislature, gave Wozencraft title to 10 million acres of the Colorado Desert. Unfortunately, the U.S. Congress failed to see the possibilities and repeatedly refused to grant him the necessary federal rights to this land. Oliver Wozencraft died an unhappy man in Washington D.C. still trying to get congress to grant him the rights that he needed to develop his land.
Several decades later, a young surveyor and engineer, Charles Rockwood, also saw the possibilities of a canal to the Colorado Desert. Rockwood met with the same success as his predecessor until, after long years of struggle, an investor named George Chaffey saw the possibilities behind the scheme. Chaffey knew the value of irrigation. He had made a fortune in the Los Angeles area planting Orange groves. Chaffey decided to underwrite Charles Rockwoods' project with $150,000.
In order to better promote the area, the name Colorado Desert was changed to Imperial Valley.
On May 14, 1901, the canal saw its first water. A lot of land was sold and people moved into the area. By 1904, the population of Imperial Valley grew to over 7,000. The agricultural production of the area went far beyond the most optimistic forecast.
Sometimes when dreams come true, the dream might actually turn into a nightmare.
The first signs of trouble came in the spring of 1904. The huge volume of silt which the Colorado carried with it found its way into the canal. By 1904 a 4 mile long section of the canal had become clogged with this silt. Efforts to keep the canal clear were in vain. In the fall and winter seasons the water flow of the Colorado subsided. The rivers flow into the canal completely subsided. A huge fortune in crops died due lack of water.
Rockwood decided to remedy the problem by building another canal. At first this worked. Then the dream turned into a nightmare of epic proportions.
In March 1905, the spring flooding season began and the Colorado River broke through the second canal. A small lake began to form in the Salton Sink. As more water accumulated, the Salton Sink became the Salton Sea covering about 150 square miles in 60 feet of water. By November 1905, matters got worse. By this time time over 150,000 cubic feet per second flowed through the canal. The Colorado River was now flowing into the Imperial Valley instead of the Gulf of California.
Instead of huge tracts of bountiful, irrigated croplands, this disaster promised to turn the area into a huge inland sea. Maybe the fishing might be good? Could things have gotten worse? Yes.
It began as a small waterfall not far from where the river poured into the Salton Sea. It was an erosion process know as the 'cutback' was beginning to make its effects known. The consequences of the cutback was likely to destroy huge sections of southwest Arizona and southeast California. the sandy soil could not withstand the force of the water running over it. Trying to 'equalize' its descent into lower elevations, the river started to erode its way back to its highest point. Or until some solid enough strata was reached to slow down the process. The accumulated silt deposits were not solid and there was no way to stop the process of erosion. In fact it was speeding up. The once tiny waterfall reached a height of 100 feet and was cutting through the desert at the rate of 1 mile a day. If the cutback reached the intake, the falls would be 300 feet high. the river channel would be so deep that the Colorado would never be able to return to the Gulf of California.
Some geologists, seeing that the same conditions existed throughout the whole area, predicted that the cutback would not stop at the canal intake. It could eventually carve a canyon 1 MILE deep and several hundred miles long! Sort of another Grand Canyon to go with the new inland sea.
Under pressure from Theodore Roosevelt, E. Harriman, Robber Baron owner of the Southern Pacific, made his money, engineers and facilities available to stop this disaster. It took 2 years and 3 million dollars to put the Colorado back in its original channel. On February 10, 1907, the breach was finally closed.
The nightmare had finally ended, for now.
Less than two years later the Colorado again began flooding the valley. It looked like it was going to be a repeat of the 1905-1907 episode. Finally, in 1910, the U.S. Congress, appropriated $1,000,000 to build a chain of levees to give this problem some temporary relief from the flooding.
This chain of events
proved two things. The possibilities that were available
and the necessity to control the moody Colorado River if
these possibilities were to be ever achieved.