The Salton Sea

The Salton Sea, of course, is a lake, not a sea. Moreover, it’s the largest lake in California, covering approximately 375 square miles. It’s also a relatively recent phenomenon, one that was created when a dike along the Colorado River failed in 1905, allowing the river to drain to the Salton Basin.

From the perspective of geologic time, though, the Salton Sea is nothing new; it’s simply the latest manifestation of a long series of wet and dry cycles that have characterized the Salton Basin. Lake Cahuilla, a much larger version of the Salton Sea, came into existence when the Colorado River shifted its course toward the Salton Basin more than a thousand years ago. The river poured its full volume into the basin for centuries, creating a 2,000-square-mile lake rich in fish, shellfish and wildlife, and sustaining a large population of Amerindians. When the Colorado River again shifted its course, Lake Cahuilla evaporated over several decades; the Salton Basin returned to a dry state shortly before the Spanish conquest of the Americas.

salton_seaUnlike Lake Cahuilla, the Salton Sea has not been replenished by steady inflows of fresh, clean water. Most of its recharge is from agricultural drain water that is delivered via the Alamo, New and Whitewater Rivers. Given its origins, this water is heavily contaminated with nitrates and pesticides. Nevertheless, the Salton Sea is one of Southern California’s most important wildlife habitats, particularly for birds. More than 400 resident and migratory avian species rely on the Salton Sea; during the winter, the sheer numbers of staging waterfowl, particularly snow geese, can be awe-inspiring.

At one time, fishing likewise was spectacular in the sea. When the lake was created, the water was only slightly saltier than the ocean; several species of salt water game fish were introduced, including the highly coveted corvina. For many decades, the sea was a favored destination for South State sport anglers, and even supported a robust commercial mullet fishery. But increasing salinity and contamination exerted a heavy toll of the fish. By the late 1990s, corvina were functionally extinct. Today, the only game fish that survives is the tough and pollution-resistant tilapia.

In 2003, approval of a package of water conservation and transfer accords known as the Quantification Settlement Agreement (QSA) reduced California’s diversion of Colorado River to its original 4.4 million acre feet. (See C-WIN white paper on the QSA.)

Though the QSA is a critical agreement that reduces unsustainable water use, it does entail clauses that affect the Salton Sea. Under the terms of the QSA, the sea receives “mitigation” water from the Imperial Irrigation District. These deliveries, however, will be curtailed in 2018. Shoreline recession already is accelerating because Imperial Valley farmers are irrigating less, reducing the drain water that is now the sea’s main source of recharge. Also, Mexico is reclaiming much of the drain water that formerly ran to the sea from the New River, further reducing inflows.

The receding shoreline has dire consequences for the millions of birds that rely on the sea for sustenance and breeding habitat. A shrinking sea salton_sea_sra2also could cause significant threats to public health. Ultimately, more than 100,000 acres of dry lake bed, or playa, could be exposed due to the receding waters. The soils of the sea’s playa are extremely fine-grained and laced with salt, toxic elements such as selenium, and fertilizer and pesticide residues. Fierce desert winds can blow this highly dangerous dust high into the air, menacing the pulmonary health of people living in the Imperial Valley, a region with childhood asthma rates that already are three times greater than the California average.

So what’s the ultimate fate of the Salton Sea? Efforts are underway to reverse the decline of the sea’s physical dimensions and ecological integrity. The State of California has provided funds to mitigate both long-standing environmental problems and the more recent impacts of the QSA; and in early 2016, the California Natural Resources Agency and the U.S. Bureau of Reclamation announced collaboration on a Memorandum of Understanding aimed at restoration of the sea. It remains unclear whether these initiatives will prove successful.

From a broader perspective, however, the dilemma facing the Salton Sea is simply a local expression of a regional problem: The disconnection between water supplies and water demand in the American West. Until we establish parity between available water and water rights claims, we will suffer from increasing shortfalls that will devastate our environment and economy.