The largest lake in California is slowly fading away, and that’s bad news for local residents. As the Salton Sea’s water sources dwindle, southern Californians are bracing themselves for toxic dust storms, noxious smells—and disease.

The Salton Sea is massive, but shallow, artificial lake located on the San Andreas Fault, some 125 miles (200 km) southeast of Los Angeles. It was accidentally created in 1905 in an effort to increase water flow into the area. But owing to policy changes in water apportionments, its overall water level has been steadily declining, and is expected to decrease significantly over the next six years. Conservation, drought, and water laws are all contributing to the problem.

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Frighteningly, the drought is not only threatening the economic vitality of the region, it’s also poisoning local residents. Over the years, the lake has served as a sump for fertilizer-and pesticide-laden runoff. As the lake shrinks, thousands of previously submerged acres are suddenly becoming exposed. It’s feared that dust storms will carry fine particles over a wide area, spreading toxins and noxious odors, while contributing to diseases such as asthma.

The before-and-after false-color pics shown above were acquired by satellites over a span of three decades. The first was taken on May 31, 1984, the second on June 14, 2015. NASA explains more:

Tim Krantz, an environmental studies professor and Salton Sea expert at the University of Redlands, notes that the most obvious changes have been to the lake’s southern shoreline. Deltas of the New and Alamo rivers are fully exposed in 2015, whereas in 1984 they represented proper “bird-foot” deltas. The deltas were exposed due to a 2.4-meter (8-foot) drop in the lake’s surface elevation since 1984. The lake spans 960 square kilometers (370 square miles), but it is shallow—just 16 meters (52 feet) at its deepest point. This makes it extremely sensitive to even slight reductions of inflow. As a result, vast expanses of the lakebed are easily exposed.

“The changes from 1984 to 2015 are the result of other water conservation activities in the watershed, such as wastewater treatment going online in Mexicali, and lining of the Coachella and All-American diversion canals from the Colorado River,” Krantz said. “These are all good things, but they mean less water in the Salton Sea.”

Areas of agriculture around the lake have changed as well. Healthy plants with active chlorophyll are highly reflective in the near infrared; they appear red in these images. Over 30 years, a greater amount of agricultural land has become brown and fallow, particularly along the southwestern shoreline.

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In response to the looming catastrophe, activists, politicians, and water officials have pleaded with the state water board in Sacramento to do something about it, but progress has been slow, if not non-existent.

[ NASA Earth Observatory | LA Times ]


Email the author at george@gizmodo.com and follow him at @dvorsky. Top image by NASA Earth Observatory images by Jesse Allen, using ASTER data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team, and Landsat data from the U.S. Geological Survey.

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