Salinity

Reduced inflows to the sea will cause a rapid rise in salinity as the recession of the Sea results in the concentration of a century’s worth of salt already accumulated in its waters, and on the lake floor. According to recent modeling efforts, at the current rate of salt loading and without reductions of inflow, salinity will increase from its present level of 44,000 mg/L to about 60,000mg/L by 2060. As the salinity level approaches 60,000 mg/L, the fishery may collapse entirely, causing the death of tens of millions of fish, and the birds that feed on them, within a few years from salinity toxicosis. With reduced inflows to the Sea, the rise in salinity would be much more rapid, reaching this threshold perhaps by the year 2017 with a reduction of only 300,000 acre-feet, or possibly sooner with a reduction of 500,000 acre-feet.

Reduced Inflows

Proposed water transfers to metropolitan areas of Southern California may result in reductions of inflow to the Salton Sea. Presently, a proposed transfer, together with the other actions listed below, may result in reductions of inflow of as much as 500,000 acre-feet of water from the 1.346 million acre-feet (MAF) that sustain the Sea today. The Salton Sea Database Program has modeled these reductions and their resulting drawdowns using bathymetric data from the U.S. Bureau of Reclamation and inflow data from the Imperial Irrigation District. The results of reduced inflows from the transfer (300 KAF (thousand acre-feet)) and the cumulative reduction of 500 KAF from all causes were modeled.

A reduction of inflow by 300,000 acre-feet as a result of the proposed water transfers would lower the Sea by 19 feet, to 246 feet below sea level, exposing 54,900 acres (86 square miles) of land.

A reduction of inflow by 500,000 acre-feet from all causes would lower the Sea by 30 feet (more than half of the total depth), to 257 feet below sea level, exposing 89,500 acres (140 square miles) of land.

Shoreline Drawdowns

The area’s most affected by elevation drawdowns would be the shallow deltaic and back-bay deltaic areas around the mouths of the inflowing rivers. The shoreline would withdraw by as much as three to five miles along the south shore, impacting the existing wildlife habitat at the Sonny Bono Salton Sea National Wildlife Refuge and the Imperial Wildlife Area. Mullet Island--the only island in the Sea providing a permanent, protected place for ground-nesting birds, such as brown pelicans--would be exposed to the mainland and depredation by predators with a drop of only seven vertical feet.

Eutrophication

Nutrient-rich runoff from nearly 650,000 acres of farmland enters the Sea through a number of agricultural drains. These nutrients lead to the excessive growth of algae and other microscopic plants. These plants thrive and become the base of the aquatic food chain that powers this ecosystem.

During the summer months, temperatures at the Salton Sea reach extreme levels, often reaching temperatures of 120F or higher. These extreme temperatures and long hours of uninterrupted sunlight increase the metabolism of plant life, further enhancing plant growth. This excessive plant growth leads to enormous algae blooms, often covering nearly the entire surface of the Sea. As the algae dies, microorganisms break down the algae, but require a large amount of oxygen to complete decomposition. Algae blooms can often block out the sun, killing other aquatic plants and further reducing oxygen levels by eliminating their respiration. Algae blooms at the Salton Sea are often cyclical in nature, in that during the summer, an entire series of algal blooms and die-offs can occur, further stressing the environment and the fish that live there. Fish are literally suffocated from the lack of oxygen in the water. Fish die-offs, in which millions of fish die in just a few days, are common during the summer months, but can also happen in the winter. As fish carcasses decay, the nutrients bound up in their body tissues are released, further increasing the nutrient levels in the sea.

It is believed that botulism spores, which occur naturally in tilapia, germinate in the intestinal tracts of sick and dead tilapia. These dying fish become easy prey for fish-eating birds, such as pelicans and herons, which then ingest fatal doses of the botulism toxin. This toxin kills the birds quickly as it paralyzes the muscles.

Air Quality

Reductions of inflow to the sea would expose several thousand acres of lake bottom sediments to the air. These very fine sediments may become windborne, creating dust storms, impairing air quality, and ultimately impacting human health. Some of these particles are so small that more than 200,000 could fit into the space of a cube of sugar. Called PM10, for particulate matter less than 10 microns (10 millionths of a meter) in size, it is one of the major types of air pollution. Currently, the Salton Basin greatly exceeds both the Federal and State of California standards for PM10. These levels would be significantly increased with the exposure of these lake bottom sediments to the winds that are a regular part of the environment in the Salton Trough. Worsening of asthma in childhood and increased death rates among elderly people are known effects of this kind of air pollution. Currently, Imperial County’s asthma hospitalization discharge rate is more than twice as high as the average for the entire State of California. Approximately 2.2 million Californians suffer from asthma, and it is the leading cause of hospital admissions in young children. In addition, any contaminants, organic or inorganic, sequestered in these sediments, are then subject to aerial redistribution, meaning that these pollutants will be free in the air humans breathe, causing further deleterious effects on human health.

The prevailing winter winds at the Salton Sea could potentially deposit these exposed sediments on people and farmlands in the Imperial Valley, which would have devastating effects on farming and therefore, food supplies. During the summer, storms from the southeast could cause blinding dust storms in the Coachella Valley and resort communities at the north end of the sea. Evidence of these conditions is present in the region in the form of sand dunes on the eastern margin of Imperial Valley (the Algodones Dune complex), sand sheets on the north east side of the Sea, and small sand dunes at the Salton Sea Test Base on the western shore of the Salton Sea.

More Information

For more information see the online Salton Sea Atlas.