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California’s Salton Sea is shrinking because of Colorado River water shortage, research finds
The water levels of California’s most polluted lake, the Salton Sea, have been dropping for more than two decades, exposing people in nearby communities to toxic chemicals.
Now, scientists might have finally figured out why the lake has been shrinking.
In a study recently published in the journal Water Resources Research, a team of researchers from the University of California, Riverside argue that the lake’s shorelines are receding due to a decrease in water flow from the Colorado River.
The Colorado River, which supplies 40 million people with drinking water and irrigates 5 million acres of farmland, is currently in crisis. A shrinking snowpack and sparse rainfall have contributed to a drop in the river’s water flow, which is now down by 20 percent compared to the 1900s.
As a result, the two largest reservoirs that get their water supply from the river, Lake Mead and Lake Powell, are about a third less full than their capacity.
In fact, water levels at lake Mead have dropped so low things like sunken boats, human skeletons, and even volcanic ash have been exposed in the lakebed that is at least 12 million years old.
To figure out why the Salton Sea’s water level has been decreasing, the UC Riverside team created a model of the lake’s water system to account for all the processes in its surrounding area that impact water balance, including climate, soil type, land slope and plant growth.
Researchers also incorporated data from nearby streams and land areas that drain water into those streams.
“There is less water coming from the Colorado River into the Sea, and that is driving the problem,” said Hoori Ajami, a University of California, Riverside hydrologist, and lead investigator for the study.
Most hydrologic models have some difficulty in accurately simulating streamflow into dry basins like the Salton Sea, according to Bart Nijssen, a professor of civil and environmental engineering at the University of Washington who was not involved in the study. But Nijssen called the UC Riverside model “robust.”
It is unclear though if the reduced flow to the Salton Sea is the result of climate change drying out rivers or more water being diverted, researchers note.
Both climate change and reduced water usage in agriculture have been linked to receding shorelines in endorheic lakes, where water flows in but not out, like the Salton Sea.
— Updated Oct. 13 at 7:16 p.m.
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