Salt farming in California

The irrigation project that gave the US a new sea

Engineers who wanted to bring water to a Californian desert didn't bank on creating a new sea.

One of the things I like most about engineers is their willingness to take on projects of such a scale as to make mere mortals tremble. "Let's build an island" "let's cut this continent in two" "let's go to the Moon for lunch" – these are the sort of things that I expect engineers say all the time at dinner parties. And once they've finished the coffee and mints they casually stroll outside and make a start. But would even the most ambitious of engineers set about creating an entire sea?

Strangely enough, in 1905 a Canadian company did exactly that, although to be fair that wasn't exactly what they were trying to do. The Californian Development Company wanted to bring about one of mankind's great dreams – greening the desert. In this case it was the Colorado desert, whose silty soils promised great fertility if enough water could be found to irrigate them. Groundwater had proved insufficient so the CDC turned to a more impressive source – the Colorado river.

The plan was simple. The Colorado river, which normally drained into the Gulf of California, sometimes broke its banks and drained into the dry Alamo river bed which, in turn, emptied into a low area of the desert known as the Salton basin. All that was needed was to canalise the Alamo and permanently connect it to the Colorado so just enough water could be taken out for irrigation.

In 1900 work began on what was christened 'The Imperial Canal' which would take water to a part of the basin now also dubbed 'Imperial Valley' in the hope that this might entice Californians to come and live in what still looked suspiciously like a desert. With temporary wooden headgates ('Chaffey gates', installed by chief engineer George Chaffey) in place, the canal was cut, bringing its first water to the valley just a year later. By 1902 the flow had been increased and the desert was indeed in bloom, attracting farmers from across the state.

But all was not well in Imperial valley. The first section of the canal began rapidly to fill with sand, eventually reducing the flow of water to a trickle. With newly installed ranchers threatening to sue the CDC, urgent action was needed. The job fell to one CR Rockwood, the other main engineer on the project. Rockwood was not a total fool, which is fortunate as his bosses' solution to the problem had been to instruct him to dynamite the Chaffey gates, something he very wisely refused to do. But the silted gates were preventing water entering the canal so he (illegally) built a brush weir across the Colorado river to raise the height and restore the flow. This worked for a while, but the silting problem returned. Then an answer seemed to come from Mexico.

The Mexican government offered to allow the CDC to make a cut from the section of the Colorado in their territory to a point on the Alamo canal beyond the silting, in return for very generous water provision to the Mexican side of the border. The president of CDC was delighted and ordered that an open cut be made from the river to the canal immediately. Few watching the first trickle of water passing down the new cut realised, but this was a mistake. As with previous plans this one initially worked. Flow was restored to the Imperial canal and the ranchers stopped threatening to sue.

Then in 1905 a series of severe winter floods hit the Colorado river. So high did the water become that it was decided to close the Mexican cut and reopen the silted Chaffey gates. Without gates installed on the Mexican cut the only away to shut it was to dam it, but by now the water flow was so high that the dam washed away. The next dam also washed away and as the banks of the cut began to collapse so more and more of the river took a new course. By August the whole of the Colorado river was travelling down the Imperial canal into the Salton basin.

At the bottom of the canal a 5m waterfall had appeared that was rapidly cutting upstream, gaining height as it went, reaching 24m at one point. If it had reached the old course of the Colorado it is estimated it would have been an impressive 91m high, but engineers from the Southern Pacific railroad, who took over from the bankrupt CDC, managed to stem the flow.

The damage had been done. With no outflows, the raging waters of the Colorado river that had entered the Salton basin had nowhere to go. The town of Salton was no more, the ranching lands were gone and the Southern Pacific Railroad sidings had disappeared. In their place lay a vast new expanse of water. The engineers of the Californian Development Company had created the Salton Sea which today covers 1,360km2.

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