On October 28, the smog-control agency for Los Angeles and the surrounding areas, the South Coast Air Quality Management District, issued an odor advisory for the intense rotten-egg stench that was permeating the air of southern California’s Coachella Valley. The source: The state’s largest lake, the 350-square-mile Salton Sea, was burping up hydrogen sulfide, a gas created by the decaying organic matter trapped beneath the water. It was the Salton Sea’s fifth odor advisory for October alone; depending on winds, the hydrogen sulfide can be smelled as far as 130 miles away in Los Angeles.
But the smell is only one small part of a more serious public-health problem, one that has the potential to affect millions of people in southern California and beyond. The Salton Sea is shrinking, a phenomenon due partially to rapid evaporation—summer temperatures around the lake routinely top 110 degrees—and partially to the decrease in the agricultural runoff that was the lake’s primary water source.
The problem is exacerbated by both California’s ongoing drought and the shallowness of the lake: “Because the Salton Sea is so flat and shallow a vertical foot of drop can expose thousands of feet of horizontal playa,” or dry lake bed, explains Bruce Wilcox, an ecologist and the assistant secretary for Salton Sea policy, a recently created position within California’s Natural Resources Agency. As the playa is exposed, it dries quickly in the desert heat and sun; desert winds kick up the dust, creating a serious air-pollution problem. Imperial County, which houses the lake, currently has the highest asthma-hospitalization rates in the state. Because the lake has been used as an agricultural sump for more than a century, the dust also contains pesticides, and officials are concerned about the presence of potentially toxic heavy metals like arsenic.