Authorities seem to be settling on the Salton Sea, coupled with strong winds off the Gulf of California, as the source of the foul odor that spread across much of Southern California Sunday night. If that's the case then you'd better get used to it, because it will probably happen again -- unless we do something to fix the Sea.
The dwindling Salton Sea, now about 42 feet deep at its deepest point, regularly releases the same nasty smells into the Salton Basin airshed, especially during the hottest months of the year. When it's hot the Sea's algae blooms and then dies, the dead algae decomposes, the organisms decomposing the algae consume oxygen, the amount of oxygen dissolved in the water drops, the Sea's fish suffocate and die, and the shore becomes a distinctly uncomfortable place to spend time.
What caused the bad smells to attract notice outside the Imperial and Coachella Valleys this week was a strong storm than surged up from the Gulf of California. The 40-mph winds that blew northward across the Sea are thought to have churned up anaerobically fermenting sediments -- and this summer's crop of dead fish -- from the lake bottom, releasing a sulfurous stench that covered Southern California from Joshua Tree to the San Fernando Valley. People as far west as Simi Valley noticed the smell, which prompted calls to air quality management districts from concerned residents across Southern California.
The Salton Sea was created by accident in 1905, when a poorly-designed canal tapped into the Colorado River overflowed and the main flow of the River poured into the bottom of the Salton Basin. Eventually the leak was plugged, though not before more than 400 square miles of the valley was flooded.
If that had been the end of it, the Sea would likely have evaporated within a few years in the hyperarid Colorado Desert. But runoff from irrigated farms and Imperial County's cities replenished the Sea, feeding it with more than a million acre-feet of water a year -- and with nutrients from agricultural fertilizers, silt, and urban sewage. The Sea is now so nutrient-enhanced that its algal blooms can deplete dissolved oxygen in all but the top few inches of water. It's not uncommon to see the Sea's fish gasping for oxygen at the surface. Beneath that oxygenated layer organic matter decomposes anaerobically, creating hydrogen sulfide, among other things.
Winds stir up the lake's water every year, and every year the water that's full of dissolved hydrogen sulfide reaches the surface and releases the gas into the atmosphere. This stench that so upset people in the L.A. Basin is a familiar part of life in communities nearer the Sea.
Why was this outbreak of odor especially bad? A few factors combined to make this the Stench of the Century. This summer has been very hot, making the Sea shallower, killing off an extra-large amount of algae and fish, and bringing the anaerobic water layer especially close to the surface. The shallower water made it easier for wind-driven currents to scour the lakebed, stirring up even more sulfur. And an unusually persistent monsoonal wind off the Gulf not only did a very thorough job of mixing up the Sea's waters, but persisted long enough to blow the resulting odor well away from the Sea.
It was an unusual event, but it won't be for long. Those factors that made this regional miasma so special -- a long hot dry summer and a strong monsoonal storm -- are expected to become far more common as we increase the globe's temperature. Even if the Sea stays its current size, we can expect odoriferous events like this week's to become far more common.
And the Sea isn't going to stay its current size for long. Due to a deal transferring 200,000 acre-feet per year of agricultural water from the Imperial Valley to San Diego for use in drinking, and another 100,000 acre-feet to the Coachella Valley, the Imperial Valley's farmers are going to be a lot stingier about letting water run off to the Sea. Some farmers will implement water conservation techniques that keep more of the water on the farm. Others will convert their acreage to renewable energy generation. The Sea is receiving "mitigation water" as part of the transfer deal, and that's keeping it from shrinking too quickly. But that mitigation water will stop flowing in 2017. The Sea is expected to start shrinking even more dramatically almost immediately. Some experts say that the Sea's fish could be wiped out as soon as 2018, leaving behind a dwindling, anaerobic sea filled with algae and cyanobacteria that could release large amounts of sulfur compounds with every passing storm, which would persist on its trickle of agricultural runoff for more than 50 years.
As Rick Daniels, former executive director of the Salton Sea Authority, told Desert Sun reporter Keith Matheny,
"If the State does not implement the Salton Sea Restoration Plan as required by the Agreement for the Use of the Colorado River and the Sea dies, this odor will be an everyday occurrence somewhere in SoCal depending upon which way the wind blows."
But as Matheny reported in a somewhat prescient article two days before the storm hit the Sea, a bill by local Assembly member V. Manuel Perez to revive the state's stalled restoration plan for the Sea went nowhere in the most recent legislative session. Perez's bill would have transferred authority to manage the restoration plan from the Salton Sea Restoration Council -- which has been targeted for elimination by Governor Brown in a cost-cutting move, and which has not met since its creation last year -- to the Salton Sea Authority, a joint-powers agency established by the state. In the absence of clear ownership of a comprehensive restoration program, the Sea will likely languish -- especially given any effective plan's likely multi-billion-dollar price tag.
Stench is far from the only problem the dying Sea will create. An authoritative report on the Sea by the Oakland-based Pacific Institute points out that the shrinking sea will expose hundreds of square miles of lakebed, whose alkaline sediments will likely be kicked up by the wind, adding to the basin's already harmful particulate matter air pollution problem -- a dire threat to local public health. Fish kills may well increase the frequency of the Sea's avian botulism outbreaks, rending the crucial wildlife habitat the Sea provides deadly to migrating birds. Imperial Valley agriculture will suffer.
And all these effects have been known for decades, yet the Sea's supporters haven't been able to get the necessary traction in Sacramento to address the problem. Perhaps the prospect of people across Southern California having to wrinkle their noses in disgust a few times a year will help add some political leverage.
Chris Clarke is an environmental writer of two decades standing. Director of Desert Biodiversity, he writes from Joshua Tree regularly at his acclaimed blog Coyote Crossing and comments on desert issues on KCET weekly. Read his recent posts here.