During migration season, birds pack the wetlands at the edge of the Salton Sea. Ducks dive, pelicans skim across the water’s surface, and hundreds of other species stalk the shores and bob on the surface of California’s largest, and most unusual, lake.

The Salton Sea is a vast, shallow body of water percolating in the hot desert inland of San Diego and a key stopover point for many birds migrating along the Pacific Flyway. Over the years, as other wetlands along the flyway have been lost to development, drought, or other causes, it has taken on an outsized importance for migrating birds. Nearly all of California’s population of eared grebes, for example, stop over at the lake, and at least a third of all the white pelicans living in North America dip in and out of its waters on their migratory travels.

But the Salton Sea is shrinking. Because of a host of reasons climate-related, agricultural, and political, less and less water ends up trickling into the lake each year, while the hot desert sun keeps evaporating its water away. And a year ago marked the end of some state-mandated inputs of extra water that had been keeping the Salton Sea relatively full for about 15 years. Without that extra water, the lake’s shrinking will start to accelerate—making it saltier, smaller, less welcoming to the birds that rely on it during migration, and more harmful to the people who live near its shores.

“There are cascading impacts all the way down on various bird populations,” says Michael Cohen, a Salton Sea expert from the Oakland-based Pacific Institute. “Part of the message is that there's not that many places left for the birds to go—so this place is important.”

The waxing and waning Salton Sea

The Salton Sea took on its modern mien about 100 years ago, when an irrigation canal full of water from the nearby Colorado River broke open. It took nearly two years for the breach to be fixed, and in the meantime, Colorado River water gushed down into the Imperial Valley. The valley, as it happened, had no outlet, so the water pooled in a depression near its northern end, in the hollows left behind from lakes that had filled and dried that region many times over the geologic past. Eventually, the waters ballooned out, forming a vast, glistening inland lake covering over 350 square miles. And thus was born the modern Salton Sea.

But the lake was in a hot, dry part of the world where summer temperatures routinely hover far above 100F. Left to its own devices, it would have quickly evaporated away in the beating desert sun. But in the 1920s, locals decided to use the lake as a place to divert all the water that ran off the farms that carpet the surrounding valley. In essence, they put the lake on long-term life support. The district had rights to vast quantities of Colorado River water, and agriculture was booming in the valley, so in those early decades plenty of runoff went rolling downhill into the lake.

Wild birds quickly flocked to this new oasis in the middle of a desert. In 1930, a wildlife refuge was established in its fringing wetlands, and it quickly filled with birds and bird watchers. Over the years, over 400 species of birds have been spotted along the shores of the lake—nearly half of all species observed in the entire U.S.

And like the birds, tourists flocked to the lake. By the 1940s and 1950s, the Salton Sea had become a vibrant tourist site, with harbors and vacation homes dotting its shores and more annual visitors than Yosemite. The California Department of Fish and Game stocked the lake with saltwater fish—because at this point, the Salton Sea had become laden with salt from the agricultural runoff, which grew more concentrated every year as evaporation sucked away the freshwater. The fish flourished for a while, feeding massive populations of migratory birds and drawing fishing-obsessed tourists from across the country.

But the heyday couldn’t last. By the 1990s, the lake had gotten so salty that waves of die-offs left its shores littered with stinky dead fish. The shoreline had already retreated—partly because, somewhat paradoxically, agriculture had gotten more effective at using water, so less of it ran off and ended up in the lake. Tourism had slowed to a trickle.

Late-phase Salton Sea

And in 2003, a major negotiation changed the water balance even more. Much of the Colorado River water that had been going toward farming in the Imperial Valley got traded away to urban areas in San Diego and the Coachella Valley, feeding showers and toilets rather than alfalfa and carrots. That would mean even less runoff would end up in the Salton Sea. Managers predicted that the lake would shrink by about a third when the full water loss was felt.

Restoring Flows to Depleted Ecosystems Sandra Postel works tirelessly to help the Colorado River once again fulfill its destiny of reaching the sea.

But to soften the blow, the state ordered the water managers to fill the water gap for 15 years—until the end of 2017—providing enough water to keep the lake from getting unbearably salty. So the water managers paid farmers to refrain from farming on some of their land, using the water they would have fed to plants to add to the Salton Sea instead. But that deal ran out last year on December 31. And so, with the new year, began a new era for the lake: One where it fills out a much smaller footprint and must deal with its ever-increasing salinity.

The new reality—and the debate about solutions

The full extent of the new reality for the Salton Sea hasn’t yet fully manifested, says Bruce Wilcox, a secretary with the California Natural Resources Agency who oversees Salton Sea policy. The lake’s surface has dropped about twice as much this year as it did the year before, but it will take some time to really feel the impacts, he says.

But the future is going to be challenging under the best of circumstances, Wilcox warns. Over the next decade, the lake is projected to shrink by thousands of acres each year, exposing nearly 100 square miles by 2028, and nearly triple its current salinity—unlivable for most things that live in water and inhospitable to anything else along its shores.

The loss of the water was not a surprise: some variant on this plan has been in the works for decades. Shoreside debates have raged over how to manage the shrinking lake. Some want to fill it back to its mid-century depths, in an attempt to recapture its glitz and glamour. Others want to do whatever it takes to keep the wetlands habitat intact.

Currently, the state has a plan in place to reconstruct wetlands over about half of the area that will be exposed in the next decade. But so far, the plans have been stalled, with only one project on the southern end of the lake inching forward.

But all it will take is action, says Cohen. “It’s a pretty straightforward concept,” he says. “Once you put up the water and build the wetlands, the birds respond quickly; there’s a huge explosion of biological activity.”

And at the same time, the costs to human health from a shrinking lake have grown more obvious. As the lake recedes, it leaves behind vast swaths of playa, full of fine-grained material that had collected on the lake bottom over the last century. Wind kicks up dust from the playa, which irritates lungs and is loaded with all the compounds and materials that have run off from agricultural lands over the years. Exactly what’s in the playa dust and what that does to human lungs is not yet fully known, but it could include a slew of organic compounds and minerals that exacerbate the already high asthma rates in the county.

“We think there is something else besides the mineral composition that’s causing health impacts,” says Roya Bahreini, an atmospheric scientist at the University of California, Riverside, who has been studying the dust from the region. “But we don’t know what it is yet.”

All plans to deal with the shrinking lake focus heavily on tamping down the playa dust. “Now, this is a desert, so we will never stop dust from blowing,” says Wilcox. But many different strategies—from dumping water on the surface to building landforms that interrupt the winds’ path over the dusty playas—are being tested and, hopefully, implemented soon, says Wilcox.

The whole project is a mess of urgent needs, says Wilcox. “It's like a big envelope of Jello,” he says. “If you push in one area it pokes out in another area.”