A large, landlocked, and very salty body of water at the southern end of the U.S. state of California, the Salton Sea has been a tourist hotspot, a birdwatcher’s dream, a fishing destination, and the site of a U.S. Navy base. Today, it is best known as California’s largest body of water, a critical habitat for migratory birds, and the single greatest ecological disaster to have ever happened in the state.

The Salton Sea is a shallow, saline lake located in the California desert. It fills the Salton Basin, which itself is a remnant of a past lake — Lake Cahuilla — that dried up around 1580. To the south, vast agricultural fields straddle the sea’s shore. The Anza-Borrego Desert State Park borders it to the west, and to its north lies Coachella Valley. It is a body of water stretching 35 miles by 15 miles, which can go up to 40 by almost 20 miles in particularly wet years.

How it started

Although its sheer size may not show it, the sea as it is today is not completely natural in origin. Geological evidence shows that this area has filled up, dried out, and been refilled several times throughout the Earth’s past as the Colorado River meandered through or around it. The rich quantities of silt this river carries would deposit around the area of the sea, effectively cutting the Colorado off from flowing into it. To the best of our knowledge, the last time such a build-up happened, and the sea dried out, was around 1580.

But silt deposits make for excellent farmland. So, around the beginning of the 20th century, farmers were moving in and breaking ground in the hot, desert climate of California’s Imperial Valley. They were, however, missing water to irrigate the crops. The California Development Company was there to help. It dug two gorges to supply the much-needed liquid from the Colorado River to the farmlands. These gorges were not equipped with floodgates; what use could such devices possibly be in a desert? Around 1904, the channels became unusable, as they were choked up with silt deposits from the river. Another gorge was dug up, again without a floodgate.

Then in the spring of 1905, due to heavy rains and snowmelt, the Colorado River flooded. The lack of protective infrastructure and the sheer volume of the flooding meant that waters broke through irrigation controls around Yuma, Arizona. They flowed into the (former) Salton Basin for two years before a line of protective levees was built by boxcars dumping boulders into the breach directly from railroads.

A lot of water had accumulated in the Salton Basin, refilling the old dry lake bed. This was the birth of the Salton Sea as we know it today.

The good days

The agricultural boom in this area during the 1920 helped maintain the Salton Sea.

Since there is no natural source of water feeding the area, the new sea would have gradually evaporated and disappeared from the map. However, croplands in the area were heavily irrigated, and water from the fields drained away into the man-made Salton Sea. Flood-irrigation — the process of dumping water on croplands through pipes or other means and letting it naturally flow over the soil — was heavily used in the area during this time, so there was a significant quantity of liquid being moved to this area, all of it draining in the sea. This counteracted the process of evaporation. Although its total volume did vary somewhat with environmental factors such as precipitation patterns, its levels were relatively constant.

The whole area prospered around, and due to, the sea. The Salton Basin lays on an important bird migratory route; the water soon grew dense with various species of fish, which these birds would eat on the way. Soon, the Salton Sea became a hotspot of birdlife, and a wildlife sanctuary was established on an area of wetlands bordering it in 1930. Birdwatchers soon followed, eager to visit this burgeoning oasis in the desert.

“Fish were initially brought into the lake with the water that originated from the Colorado River and included native species, such as carp, rainbow trout, striped mullet, humpback sucker, and desert pupfish,” Fishbio explains. “As early as the 1930s, native fish had begun to die off because they couldn’t tolerate the high salinity, but this didn’t deter tourists. Salt-tolerant sport fish such as corvina were introduced, luxury homes were built, a yacht club was established, and a resort destination was born.”

In 1930, a wildlife refuge was established on some wetlands along the edge of the lake that had attracted many birds. The fish flourished in the lake and provided a source of food for massive populations of migratory birds. Birdwatchers flocked to this new refuge in the middle of a desert.

Where there are people, there’s also money to be made, and the Salton Sea was no exception. Into the 1950s and 1960s, the area would become a popular resort destination. Hotels and clubs would be built along the shores of the sea, alongside homes, vacation houses, schools, shops, and other infrastructure. Sport fishing, yachting, water skiing, and golfing attracted 1.5 million visitors to the area every year during its golden age.

Where it went wrong

The going was good in this area while enough water was being pumped, one way or another, into the Salton Sea.

Arguably, however, the beginning of the end came in 1936, with the completion of the Hoover Dam. In 1938, the Imperial Dam was also completed; together, these two ended the occasional flooding of the Imperial Valley area by the Colorado River and irrigation infrastructure built in the area. This was the first meaningful reduction in water input towards the Salton Sea.

As there is no natural effluent draining into the sea, evaporation instead served to reduce its volume quite significantly, and quite fast. Further compounding this issue is that the Salton Sea is quite shallow but very widely-spread, meaning evaporation can take place very quickly here relative to most other bodies of water. As its waters evaporate, minerals in the sea such as salt become concentrated.

The Salton Sea also belongs to a class known as terminal or endorheic drainage basins, meaning water from a wider area pools into it and stays there. In other words, salts leached by waters from the whole basin gradually make their way into the Sea.

Since water flowing into the Salton Sea was used agricultural water, there was a significant quantity of salts and fertilizers being brought into it on a daily basis. Together with a lower total volume of liquid reaching the sea by this time and its endorheic nature, the end effect was that the Salton Sea was becoming saltier by the day.

Beginning with the 1970s, researchers were already warning that great problems were on the horizon for the Salton Sea due to this gradual increase in salinity.

In the mid 1970s, several powerful tropical storms caused the sea to flood over, severely damaging buildings and infrastructure of the communities that had sprung up along its shores. This dramatically reduced the area’s ability to attract and host tourists, hamstringing its economic potential. Many businesses in the area were abandoned following this event.

Soon after, the previous warnings came true. Before the 1980s rolled around, fish started to die off in droves, unable to bear the high salinity. Large algal blooms, fueled by the fertilizers making their way into the lake, consumed what little oxygen there was left (salty water can dissolve far less oxygen than freshwater), virtually wiping-out the remaining fish populations. According to recent estimations, of an initial population of 100 million fish, a staggering 97% died off by the 1990s.

Their carcasses laid in piles all along the shorelines.

The lack of fish heavily affected bird populations which relied on the sea for food. Furthermore, the staggering levels of death in the waters led to an epidemic of botulism ravaging what little fish stocks were still present in the Salton Sea, which later spread to the birds around 1996. Over a four month-long period during that year, over 10,000 birds died at the site; incinerators were running around the clock during this time to dispose of the infected dead bodies.

After the year 2000, various policies and improvements in water use in the surrounding farmlands led to a further decrease of around 40% in the amount of water flowing into the area. This exacerbated the problems the sea was facing, leading to an even more drastic increase in the salinity of its waters and the associated environmental impact this was having on wildlife.

The repeated issuing of bad odor advisories for the Salton Sea puts into perspective just how much death local wild communities experienced here since the 1970s. In 2012, after a strong storm had agitated the waters, the foul smell of decaying organic matter could be suffered as far as the Los Angeles Basin, some 150 miles (240 km) away.

The area today is plagued by severe air quality issues, in very large part due to toxic dust raised from the large surfaces of now-exposed lakebed. While the exact composition of this dust is unclear, it is safe to assume that it consists of a combination of decaying organic matter, salts, and dried compounds accumulated over years from farming runoff.

Several reclamation and rehabilitation projects have been proposed in the area, but they routinely run into the problem of funding. The problems plaguing the area are enormous, and as thus, enormously expensive to address. The funds to do so are simply not forthcoming.

Schools serving the various communities around the Salton Sea today employ a system of colored flags to keep at-risk students (such as those suffering from asthma) safe from the fallout produced by the drying sea. On good days, signified by a green flag, they can join their friends on the playground. On bad days — red flags — they’re not even allowed to exit the school buildings.

The once-bustling area is, today, a shadow of its former self. Stranded ships, half-buried in the desert soil, litter the former coast of the Salton Sea. Abandoned mobile homes sit next to the Varner Harbor, now closed due to low water levels.

“Pulling up just before sunrise at the Salton Sea, California’s biggest lake, is an almost surreal experience. At this time of day it’s eerily quiet; just the sound of water, a few desolate cries of waking birds and the sound of our Polaroid cameras,” writes Nathalie Farigu for Our World, describing the area as it is now. “Abandoned and partially destroyed mobile homes, a chair in the water, a lone boot, a pink sink and a BBQ are just some of the things lying around.”

“It makes you wonder what happened here.”

The Salton Sea is a story of happenstance and tragedy. It’s a story of what could have been, but wasn’t, and of the missing funds to set it right. Of incredible loss of wildlife, and of the people that still struggle to live under its effects. What happened here is, in short, the single greatest environmental disaster of the state of California — one whose aftermath is still playing out.