The Salton Sea is California’s largest lake, a vast, shallow body of water situated in a terminal basin in the state’s southeastern desert. This unique geographical feature has no natural outlet, meaning water leaves only through evaporation, concentrating everything that flows into it. The answer to whether the Salton Sea is toxic is yes, driven by a decades-long process of environmental collapse. This crisis is fueled by reduced water flow and agricultural runoff, creating hazards that affect the water, the exposed lakebed, and the health of nearby communities.
Pollutants in the Water
The Salton Sea is a hypersaline lake, a condition that is accelerating as water diversions and drought reduce inflow, leaving the remaining water to evaporate. This lack of an outlet means that salts and minerals entering the sea are permanently trapped, causing the salinity to rise to approximately 55 grams per liter, which is about 50% saltier than the Pacific Ocean. This extreme and increasing salt concentration makes the water inhospitable to most aquatic life.
The primary source of chemical contamination stems from agricultural runoff from the surrounding Imperial and Coachella Valleys, which flows into the sea via the New and Alamo Rivers. This runoff carries excess nutrients from fertilizers, which lead to low-oxygen conditions and massive die-offs of fish and birds. The water also contains concentrated levels of heavy metals and metalloids. Naturally occurring elements in the soil, such as selenium and arsenic, are mobilized by irrigation and subsequently flow into the sea, where they accumulate. These toxic materials settled in the submerged sediments over decades, posing a severe threat as the water recedes and exposes the contaminated lakebed.
The Airborne Hazard from Exposed Lakebed
The most immediate and geographically widespread danger comes from the exposed lakebed, referred to as the “playa,” which is a direct consequence of the sea’s shrinking size. As the water level drops, vast stretches of this former seabed are uncovered, exposing contaminated sediment to the desert wind. This exposed area is coated with fine-grained dust particles that contain the historical accumulation of toxins.
When high-wind events occur, this dry sediment is aerosolized, creating dust storms that carry fine particulate matter known as PM10 and PM2.5. These microscopic particles are small enough to be easily inhaled and penetrate deep into the human respiratory system. The dust’s composition is harmful, containing concentrated heavy metals like arsenic and persistent organic pollutants such as organochlorine pesticides.
Research has also identified a unique biological hazard within the dust: high levels of bacterial membrane fragments that act as potent endotoxins. This biological component contributes significantly to the dust’s toxicity. The aerosolized dust poses a major air quality crisis for communities throughout the Imperial and Coachella Valleys, creating a toxic plume that travels far beyond the immediate shoreline.
Health Risks for Nearby Residents
The toxic dust from the exposed playa is directly linked to a public health crisis for the nearly 130,000 people living near the Salton Sea. The most significant documented impact is on respiratory health, particularly in children. Studies show that children in the region experience rates of asthma that are significantly higher than the national average, with some communities seeing rates as high as 20% to 24%.
This high incidence of respiratory illness, including wheezing, coughing, and bronchitis, is associated with proximity to the receding shoreline and exposure to the airborne particulate matter. Researchers have found that the dust’s unique chemical and biological makeup causes severe lung inflammation. Beyond the respiratory issues, chronic exposure to heavy metals like arsenic and selenium through inhalation and potential food chain contamination presents long-term public health concerns. These toxins pose risks for neurological damage and certain cancers. The majority of residents most affected are from low-income, predominantly Latino communities, highlighting a severe environmental justice issue.
Ongoing Mitigation and Restoration Efforts
The State of California is actively addressing the crisis through the Salton Sea Management Program (SSMP), which is implementing a Phase 1: 10-Year Plan (2018–2028). The primary goal of this program is to mitigate the health and environmental risks by constructing approximately 30,000 acres of habitat and dust suppression projects on the exposed playa. The strategy focuses on two main types of interventions to stabilize the environment.
Dust Suppression and Habitat Creation
One major intervention involves dust suppression projects designed to physically cover or stabilize the highly emissive playa surfaces. This includes large-scale construction, such as the Species Habitat Conservation (SCH) project, which aims to create thousands of acres of shallow-water habitat to keep the toxic sediments submerged. Other efforts include Vegetation Enhancement Projects, which use plants to stabilize the soil and prevent dust from becoming airborne.
Water Management and Quality Improvement
The second type of effort focuses on managing the remaining water body and improving water quality. This involves constructing perimeter wetlands and conveyance features to manage the inflow of water and reduce overall heavy metal concentrations in the remaining water. These projects are designed to create a more stable, less toxic environment for the migratory birds that rely on the sea while simultaneously reducing the source of the airborne hazard.