Salton Sea: Largest Lake of California Born From An Engineering Mistake

The Salton Sea formed by accident to become a pleasure hotpot during the 1950s and '60s. Today it poses a huge threat to the local environment and economy.
Christopher McFadden

The Salton Sea is the largest lake in California at around 970 square km. But it's not the product of the powers of nature, it's the product of a major engineering mistake over 110 years ago.

Its creation wiped out the town of Salton and it grew to become a popular fishing and leisure spot during the 1950s. It also became an important local wildlife refuge.

That is until today. It is now on the verge of becoming an environmental and public health disaster. In the following article, we'll take a look at this interesting watercourse created entirely by accident.

What is the Salton Sea?

The Salton Sea is not actually a sea but a shallow, saline, endorheic (one with limited drainage that normally retains water with no method of allowing water outflow to a river or ocean), rift lake. It is located directly on top of the San Andreas Fault within the United States state of California's Imperial and Coachella Valleys.

The lake fills the lowest elevation of the Salton Basin with its surface 71.9 meters below current sea level (as of January 2018). The lake is fed by the New Whitewater and Alamo rivers and agricultural runoff, drainage systems, and creeks from the surrounding area.

The lake fluctuates in extent and depth over time depending on local precipitation and inflow rates from its sources. Its average dimensions tend to be 24 by 56 km in width and length respectively. Average annual inflow tends to be 1.5 cubic kilometers which are generally enough to maintain a maximal depth of 13 meters, give or take. 

Salton Sea view
Source: Rman 348/Wikimedia Commons

How did the Salton Sea form?

The Salton Sea is located due South of the Coachella Valley and North of the now heavily agricultural Imperial Valley. It sits in the lowest part of the Salton Basin which covers an area of 8,000 square miles of southern California and Northern Mexico. 

The soils of the area are very fertile for reasons we will explain later. This is perfect for farming except for one critical resource - abundant water.

To combat this an irrigation system was planned and construction began in 1900. A network of canals was built across the Southernmost part of the Salton Basin.

So far so good but the canals would prove to be too small to handle flood waters and were poorly built. Almost inevitably disaster struck when, in 1905, heavy rainfall combined with snowmelt poured into one of the canals from the nearby Colorado River.

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This deluge proved too much for the systems dikes and broke through the canal's headworks. Repair works began immediately and for the next 18 months engineers battled with the resultant flooding - but to no avail.

With the canal's levees now breached and no means to stop the constant gush of water from the Colorado River, flood water flowed unabated into the massive basin.

This event created two new rivers (the New and Alamo) and the freshwater lake that would come to be known as the Salton Sea. Flooding was eventually halted in 1907 but the nearby town of Salton could not be saved and was submerged.

Ordinarily, if left to its own devices, the lake would have eventually dried up. Average evaporation rates for the region are around 180 cm per annum with precipitation rates a mere 5.08 cm a year.

But that wasn't the end of the story for the Salton Sea.

In 1928 Congres needed somewhere to deposit agricultural wastewater, especially from the Imperial Valley. It was decided to use the manmade lake as a repository for this runoff a process still ongoing to this day.

Today the lakes average depth is about 9 meters.

Salton Sea from space
 Adapted from Google maps

This is not the first time there's been a lake here

The modern-day Salton Sea lies within a large geological depression, called a Graben, that formed around 5 million years ago. Its formation led to the inundation of the area by the Pacific Ocean that formed a large inland sea that covered large parts of Southern California.

Throughout the ice age of the Pleistocene, over a period of around 3 million years, a large river delta from the Colorado River formed, continually depositing sediment into the area. 

This delta eventually grew to reach the western shore of the Gulf of California and effectively created a barrier to cut the area, now called the Salton Basin, off from the Pacific Ocean in the Gulf.

Salton Sea 5 million years ago
Source: Western Washington University

The geology of the area reveals that, because of the delta barrier, the localized basin where the Salton Sea lies, has periodically been a freshwater lake, saline endorheic lake, and dry desert basin over time.

These periods correspond with periods of extended wet and dry periods as Colorado periodically changed course North and local climate changed over time. 

Cyclicity of these events appears to have been roughly every 400 to 500 years (give or take). Evidence also indicates the last natural lake to be present was around 200 or so years ago. 

The last of the Pleistocene lakes to occupy the basin was (Ancient) Lake Cahuilla, sometimes called Lake LeConte or the Blake Sea on older maps.

This lake appears to have disappeared by about 1600 as Spanish record the area as the "Colorado Desert" but do note ancient Indian legends of a lake there before.  This is also supported by an 1855 railroad survey that identifies it as "the Valley of the Ancient Lake". 

Salton Sea and Slab City
Source: Marc Cooper/Flickr

From holiday hotspot to death trap

During its initial phase of flooding, between 1905 and 1907, many freshwater fish species migrated to the new watercourse. But they soon died off as the water's salinity rose from a combination of evaporation and agricultural runoff laden with salts.

In an attempt to restock the lake local authorities stocked the now salty water with salt-tolerant fish species like Corvina, Sargo and Bairdella. This acted as a magnet for anglers who quickly flocked to the lake for recreational fishing.

These fish also attracted migratory birds who would revisit it annually during the Pacific Flyway migration patterns. By the 1960s, resorts, marinas, and yacht clubs littered the shores of the Salton Sea.

But the new, yet fragile, ecosystem would have a very short shelf life. Water in the lake had no real source of freshwater input and continued high levels of evaporation and chemical, salt and fertilizer-laden agricultural wastewater continued to pour into the Salton Sea.

Larger fish species and birds would begin to die off en masse and, in 1999, an enormous Algal bloom would sign the death warrant for millions of Tilapia as they were literally suffocated. Their corpses would continue to litter parts of the lake for the next decade.

Salton Sea dead fish
 Source: Stephen Kallao/Flickr

Things have gone from bad to worse since with salt levels now 35% more saline than the ocean (on average 35 parts per thousand) at between 50 and 60 parts per thousand. One salt-loving species, Corvina, can no longer spawn. 

If the lake ever completely dries up there are concerns that tons of harmful dust will be kicked up potentially causing a very real public health risk. That's not to mention the effects on the local economy.

 Efforts being made to "save" the Sea

Efforts have been made over the years to try to reverse or stall the impending ecological and economic disaster. In 1993 the Salton Sea Authority was formed to oversee the preservation of the lake.

Over the past few decades, the authority has been working to develop a viable and sustainable plan. This is compounded by an upcoming expiration of a key water settlement agreement after which most of the runoff supply to Salton Lake is to be diverted to San Diego and other towns in the Coachella Valley.

A pilot effort, called the SCH Project, is in the works which plan to provide clean and safe habitats for fish and birds by building new water bodies for them. These will include deep-water pools. loafing islands and integrated sedimentation basins. 

$2 Million in funds have been earmarked by California for these efforts including a feasibility study of proposed projects. An additional $200,000 was also authorized by the Obama administration for the Army Corps of Engineers to help out.