In southeastern California, spanning both Riverside and Imperial counties lies the Salton Sea, the largest inland lake in California, measuring approximately 376 square miles in area. It is home to millions of migratory birds each winter, including several endangered species. Only three miles from the San Andres fault and well below sea level, this area has been dramatically shaped by its past. Let's explore that past and how the sea became what it is today.
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A million years ago, the area was connected to the Gulf of California. When the gulf receded, it left behind a legacy of salt in the area. Over geologic time this region went through cycles of flooding from the Colorado River and drying from evaporation. During periods of flooding, Lake Cahuilla was formed, a freshwater lake approximately 6 times larger than the present day Salton Sea. Over the last 1300 years, the region was flooded and wet more often than it was dry.
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Lake Cahuilla was widely used by the local Native Americans for food and water. In some places, their fishing traps can still be seen. In the 1800's Lake Cahuilla went through another drying period and shrank substantially, exposing the salty lake bottom. These large salt flats and very fertile soil attracted western settlers to the area in the mid to late 1800s.
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Settlers took advantage of the large salt flats and fertile soil left behind, not knowing that the area was prone to periodic large floods. They built towns, farms, roads, and even railroads on the exposed lake bottom. Canals were created to bring in water for agriculture. Then, in 1905, a series of unexpected, large floods on the Colorado River breached the canals and brought the full force of the river pouring into the area.
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This flood decimated the area, but it also created the modern Salton Sea. The river flowed into the Salton Sink until 1907. The canals were rebuilt, and reinforced, and the Colorado River was redirected to its present-day course. The railroads were rebuilt around the sea and life started back up in the area.
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The new inland sea became a tourist attraction. California Fish and Game stocked the sea with marine fishes which flourished in the salty water and encouraged boating and fishing in the area. From the 1930s through the early 1970s the Salton Sea was an attractive vacation spot for celebrities and vacationers alike. The Salton Sea attracted more visitors per year than did Yosemite Park. Boat racing, bird watching, fishing, and many other water sports boomed in the area. Marinas, hotels, and numerous other establishments brought economic prosperity to the region.
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These were the glory days of the Salton Sea area. But in 1976-77, two tropical storms wiped out the recreation infrastructure. The Coachella Valley needed to be rebuilt again. But in the final decades of the twentieth century, the sea was dealt another blow. Irrigation water containing salts from the soil constantly flowed (and continues to flow) into the sea and then evaporated. This caused the salt content (salinity) of the sea to slowly, but constantly, rise.
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In addition to rising salinity levels, strong winds occasionally blow across the desert causing the anoxic bottom water in the sea to rise up to the surface creating massive fish kills. The hydrogen sulfide, brought to the surface, escapes as a gas, leading to an acrid smell most accurately described as that of rotten eggs. Most valuable sport fishing species in the sea could not survive these conditions. Of the larger fish species, only Tilapia remain.
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In 2003, under intense pressure from the U.S. and California State governments, the Imperial Irrigation District (IID), which is responsible for agricultural water distribution in the Imperial Valley, agreed to sell hundreds of thousands of acre/ft of water (14% of their supply) to coastal urban users. It was recognized at the time that this transfer would have disastrous effects on the Salton Sea and surrounding communities.
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To alleviate the adverse effects on the Salton Sea and surrounding communities, the State of California allowed IID to put extra water into the sea for 15 years in order to give the state time to address and mitigate the environmental and economic problems at the sea. In 2018 and without significant action, those mitigation flows will cease and the sea will begin a rapid decline in volume and thus lake level, and a rapid increase in salinity.
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