The Salton Sea, located in the arid southeastern corner of California, is the state’s largest inland body of water. This shallow, landlocked lake is shrinking rapidly, triggering an ecological collapse and public health crisis. The receding shoreline and increasing salinity expose vast amounts of toxic lakebed, creating hazardous conditions for wildlife and nearby human communities. The Salton Sea now represents a complex regional challenge.
The Geography of Decline: Water Levels and Exposed Playa
The Salton Sea was accidentally created in 1905 when an irrigation canal from the Colorado River breached, flooding the low-lying Salton Sink. Since then, the sea has been sustained by agricultural runoff from the Imperial and Coachella valleys. As a terminal lake with no natural outlet, water leaves only through evaporation, which concentrates salts and pollutants.
The sea’s decline accelerated following the 2003 Quantification Settlement Agreement (QSA), which transferred agricultural water to urban areas. This agreement dramatically reduced the inflow of agricultural runoff, especially after “mitigation water” deliveries ended in 2017. The loss of this supply is causing the water level to drop, exposing the lakebed, known as the playa.
The rate of shoreline retreat has accelerated in recent years, nearly tripling after 2018 compared to the 2002-2017 period. By November 2023, the total exposed playa was estimated to be over 33,311 acres. This area continues to grow, as a one-foot vertical drop can expose thousands of feet of horizontal lakebed.
Ecological Breakdown: Hypersalinity and Wildlife Loss
The lack of an outflow and high evaporation mean that salts and minerals entering the sea are left behind. This process has led to hypersalinity, making the remaining water biologically hostile. The Salton Sea is now more than 50% saltier than the Pacific Ocean, increasing at an estimated rate of about 3% per year.
This extreme salinity is destroying the aquatic food web, causing an ecological collapse. Endemic fish species, such as Tilapia, are unable to survive the increasing salt levels. The near-extinction of these fish populations has a cascading effect on the over 400 species of birds that rely on the ecosystem.
The sea is a crucial stopover location along the Pacific Flyway, serving as a rest and feeding ground for millions of migratory birds. As fish disappear, fish-eating birds like pelicans and cormorants lose their primary food source, leading to starvation and mass die-offs. The loss of this habitat is an international environmental concern, as the Salton Sea is the second most avian bio-diverse region in North America.
The Public Health Crisis: Airborne Hazards
The exposed lakebed, or playa, is a mixture of decades of sediment, agricultural runoff, and contaminants. This sediment contains hazardous materials, including naturally occurring elements like arsenic and selenium, along with traces of pesticides and heavy metals. When the playa dries out, fine particles are easily picked up and aerosolized by the region’s strong desert winds.
These toxic dust storms distribute fine particulate matter, specifically PM10 and PM2.5, across surrounding communities. PM10 particles are small enough to be inhaled deep into the lungs, while PM2.5 particles can enter the bloodstream, causing serious health issues. This wind-blown dust contributes significantly to the region’s poor air quality.
The result is a public health crisis for residents in the Imperial and Coachella valleys, particularly children. Communities near the sea have some of the highest rates of asthma and other respiratory illnesses in California. Studies show a clear association between exposure to the dust events and reduced lung function, with over 20% of children in the region suffering from asthma.
Current Restoration and Stabilization Projects
Addressing the environmental and health crisis requires large-scale intervention to stabilize the exposed lakebed and restore habitat. The primary effort is the state-led Salton Sea Management Program (SSMP), which outlines a 10-year plan to construct nearly 30,000 acres of habitat and dust suppression projects. The aim is to mitigate receding water effects by 2028.
One of the largest active measures is the Species Conservation Habitat (SCH) project, located near the New River delta. This project constructs a network of shallow ponds and wetlands to restore thousands of acres of lost habitat and suppress dust. The initial phase, including the East Pond complex, is operational, with water flowing into approximately 2,000 acres of the new habitat.
Dust mitigation techniques, such as surface roughening (trenching) and vegetative covers, are being implemented on the exposed playa to prevent the release of fine particulate matter. These projects, along with additional habitat areas like the North Lake Pilot Demonstration Project, are advancing with state and federal funding commitments. The overall goal is to improve air quality and provide environmental refuge for the birds along the Pacific Flyway.