The Salton Sea – well-known as California’s most polluted lake – has lost a third of its water over the past 25 years. As it dries up, the concentration of salt and chemicals in the remaining water has increased dramatically, leading to mass die-offs of fish and birds, including some already threatened species. Moreover, the dry lakebed, coated in the salty and toxic water, becomes dust causing respiratory issues to residents living in the lake’s vicinity.
According to a team of researchers led by the University of California, Riverside (UCR), the main reason for this massive shrinking has been a steady decline in the Colorado River flow. “It is an environmental catastrophe,” said study lead author Juan S. Acero Triana, a hydrologist at UCR.
Over the years, scientists have proposed a variety of hypotheses about why the lake’s water levels are declining. While some blame global warming for drying up Salton Sea, others suspect that agriculture could be to blame, since, as irrigation systems get more efficient and crops are modified to use less water, the quantity of water reaching the lake has declined. However, this new study argues that these are not the main causes of the decline.
“There is less water coming from the Colorado River into the Sea, and that is driving the problem,” explained study co-author Hoori Ajami, another UCR hydrologist. By using a hydrologic model which accounted for all processes in the surrounding areas that impact the lake’s water balance – such as climate, land slope, soil types, or plant growth – the scientists were able to simulate long-term water balance dynamics and identify reduced Colorado River flows as the main cause of the Salton Sea shrinking.
“It’s not entirely clear, however, whether the decline in Colorado River water is more due to global warming drying out the river, or reductions in allocation levels to California, or both,” Acero Triana said. Nonetheless, these findings should send a clear message to water management agencies and lawmakers: the Salton Sea watershed should be considered part of the Colorado River basin.
“Usually, the Sea is considered an independent system, and a watershed-centric approach considering surface and groundwater resources is needed to find a solution. As the environmental risks of a shrinking Sea mount, all parties must work together to mitigate the danger,” Ajami concluded.
The study is published in the journal Water Resources Research.
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By Andrei Ionescu, Earth.com Staff Writer