The Salton Sea spreads across a remote valley in California’s lower Colorado Desert, 40 miles (65 kilometers) from the Mexican border. For birds migrating along the Pacific coast, it’s an avian Grand Central Station. In midwinter tens of thousands of snow geese, ducks, pelicans, gulls and other species forage on and around the lake. Hundreds of other species nest there year-round or use it as a rest stop during spring and fall migration.
At the dawn of the 20th century, this massive oasis didn’t even exist. It was created in 1905 when Colorado River floodwaters breached an irrigation canal under construction in Southern California and flowed into a basin that had flooded in the past. In earlier years, the sea covered roughly 40 square miles more than its current size of 343 square miles (890 square kilometers).
Since then, agricultural runoff from newly formed nearby irrigation districts has sustained it. By midcentury, the sea was considered a regional amenity and stocked with popular sport fish.
Now, however, this resource is in trouble. Wasteful irrigation practices that maintained the sea have been reduced, and excess water is now being transferred to thirsty coastal cities instead. The sea’s volume has declined to roughly 4.6 million acre-feet, losing nearly 3 million acre-feet since the mid-2000s. (An acre-foot is about 326,000 gallons – the amount of water required to cover an acre of land to a depth of one foot).
As water evaporates from its surface, its salinity has spiked: The sea is now almost twice as salty as the Pacific Ocean.