Southern California’s Salton Sea, the largest lake in California, has seen its share of ups and downs since it was accidentally created in 1905 by Colorado River floodwaters. Now, already badly polluted by chemicals from agricultural irrigation runoff, which provides the lake’s inflow, the surrounding shoreline is in danger of becoming a toxic blight.
Reduced inflows are shrinking the lake’s surface area, creating serious health consequences for both the diverse wildlife of the area and the approximately 600,000 people who live nearby. While the state has a plan to head off what could become an environmental disaster, it depends, in part, on uncertain funding and the results of a promising but still experimental new technology to remove selenium – one that could prove useful in many other settings in the Western U.S. and around the world.
The stakes are high. Selenium, a naturally occurring mineral that is often present in irrigation runoff, can be toxic in high doses. It was responsible for the deaths of huge numbers of birds, fish, plants and other wildlife at the Kesterson Reservoir in the San Joaquin Valley in the early 1980s, a disaster that still reverberates with environmentalists more than 30 years later. And if a solution to selenium contamination at the Salton Sea is not found, Southern California’s Riverside, Imperial and San Diego counties could face a similar situation.
Securing the Playa
The shores of the sea have been receding at a rate of about 1ft a year, according to Bruce Wilcox, assistant secretary for Salton Sea policy at California’s Natural Resources Agency. That rate is expected to double in 2018, as a deal that has provided 800,000 acre-feet of fresh water over 15 years is due to expire. The water was a temporary remediation effort to ease the impacts of a large water transfer agreement between the nearby Imperial Irrigation District and San Diego, which reduced the flow of irrigation runoff into the lake.
The receding waters are already exposing a “playa” surrounding the sea, consisting of, among other things, a superfine dust less than 10 microns in diameter, or less than one-fifth the width of a human hair. The EPA is studying the toxicity of that particulate matter, or PM10, as it’s known, which can be dangerous because it is small enough to be inhaled deeply into the lungs.
Organizations like the Asthma and Allergy Foundation of America and others are concerned that the release of more PM10 will exacerbate the region’s already high rates of asthma and other respiratory conditions. And, according to Wilcox, the areas of most concern are occupied largely by “economically disadvantaged folks who don’t really have the ability to move anyplace else.”
To prevent the release of particulate matter, the state plans to create wetlands around the sea. But in order for the wetlands plan to work, the selenium that contaminates the Alamo and New rivers, which provide most of the inflow to the sea, would need to be reduced to 2 parts per billion (ppb).
When selenium flows into marshes and wetlands, it is easily taken up by algae and bacteria that are in turn consumed by higher-order wildlife. When present at high levels, selenium eventually moves up the food chain to cause severe birth defects in waterfowl and impaired reproduction in fish populations. At Kesterson, a reservoir that the state built to capture agricultural runoff similar to that which flows through the Alamo and New rivers, selenium toxicity in 1983 resulted in a 64 percent rate of deformity and death of embryos and hatchlings of the area’s wild aquatic birds, according to the United States Geological Survey. While the levels found in the Alamo and New rivers are probably not as high as at Kesterson, they are high enough to produce grave concerns, according to Tim Bradley, a University of California, Irvine, professor of ecology and evolutionary biology, who has served on the Natural Resource Agency’s science advisory committee.
Getting Beyond the Beaker
Reducing selenium levels in the Salton Sea is key part of long-term remediation efforts and one of the best hopes is Crystal Clear Technologies, an Oregon company that has developed a new remediation technology. Its proprietary filtering material, known as NMX (for Nano Media Extraction), has been shown in tests to be effective at removing selenium. The state is considering a pilot treatment facility using Crystal Clear’s technology, tentatively scheduled to begin in the second quarter of 2018, that would process 50 gallons of water a minute from the Alamo River as it flows into the Salton Sea. Should that pilot prove as successful in the field as results have been in the lab, one or more larger plants – handling up to 100 times the flow – could be built at the sea.
Crystal Clear’s NMX uses chitin, a fibrous substance found in crab and shrimp shells acquired as waste from the seafood industry, to remove selenium from water, and requires a contact time of as little as five minutes (in contrast to contact times that can range from 30 minutes to weeks or much longer, depending on the contaminant and treatment technique). A short contact time would let a selenium-removal plant process more water, faster. A full-scale plant could process a flow as high as 5,000 gallons a minute on each river, according to Crystal Clear.
While other technologies are under consideration for use at the sea, Crystal Clear’s technology has been in tests at Arizona State University for three years, and is currently able to achieve 3 ppb on samples from the region, according to Lisa Farmen, Crystal Clear’s chief executive.
While a pilot plant could be built in three to four months, “it’s going to take some clout far beyond what we can do in a beaker” to provide enough freshwater for the wetlands plan, Farmen says. And by clout, she means money.
While costs for the state’s 10-year Salton Sea Management Program could eventually range from about $400 million to as high as $1 billion, according to Wilcox, there is currently only about $60 million available, and further funding is envisioned from an uncertain (and not yet secured) patchwork of bond measures, philanthropic organizations, partnerships and other sources.
Clean Water for Fresh Air
If funding for selenium remediation cannot be secured, the potential toxicity of the playa around the Salton Sea would affect an area renowned for its biodiversity, which hosts perhaps the most diverse and important population of bird life in the continental U.S. “One thing that makes the Salton Sea important is the fact that it is the most important feeding site and resting site for birds that migrate up and down the Pacific Flyway,” said Bradley.
Even if the state can find funding, the plan calls for only about half the “dusty beaches” to be covered by wetlands, Bradley says. Whether the beaches are secured or not, the health effects of the exposed playa could be felt from Los Angeles to Arizona, and they may well not be minor. Bradley compares the situation to that at Owens Lake near Death Valley, which was drained a century ago to provide water for Los Angeles, and has been called the single largest source of dust pollution in the U.S. Bradley also cites Russia’s Aral Sea, which lost 90 percent of its surface area to irrigation, creating a toxic desert that has led to serious health problems for the surrounding population.
“There are a number of examples around the world of what happens when you dry up a salt lake and how disastrous that is for a region,” Bradley said. “California is well on its way to doing exactly that. It’s really quite concerning.”
This article was updated to correct the mitigation water provided to the Salton Sea was 800,000 acre-feet over 15 years.