Why does the Salton Sea turn into poisonous dust?

The Salton Sea, California’s most polluted inland lake, has lost a third of its water in the past 25 years. A new study has identified a decrease in the flow of the Colorado River as the cause of this decline.

When the Salton Sea, a salt lake and enclosed body of water, dried up, the concentration of salt and chemicals in the remaining water soared, leading to massive deaths of fish and birds, including endangered species.

The dried layer of the lake, covered with poisonous salt water, turns into dust, causing breathing problems in geographically close populations.

“This is an ecological disaster,” said Juan Acero Triana, a hydrologist at the University of California and lead author of a new study aimed at understanding the movement of water on and under the Earth’s surface near the Salton Sea.

There are many hypotheses about the cause of the ongoing decline in water levels.

Some blame climate change and heat for the lake’s drying up. Others believe that agriculture may be the cause.

Although irrigation systems become more efficient when using less water, the amount of water reaching the Salton Sea, California’s largest lake, is decreasing. However, scientists say this is not the most plausible reason for low sea levels.

“There is less water coming from the Colorado River into this sea, and that’s what’s causing the problem,” explains Hori Ajami, a hydrologist at the University of California, co-author of the study and principal investigator.

These scientists looked at all the major processes that affect the water balance of an inland lake such as the Salton Sea.

It is worth noting that the water surfaces of endorheic lakes around the world have shrunk over the past decades, in what scientists call a “worrisome” trend due to the multiplicative effects of global warming and diversion of water for agricultural and industrial purposes.

To understand why the Salton Sea is deteriorating, the scientists in the study used a hydrological model that takes into account all the processes in the surrounding areas that affect the lake’s water balance, including climate, soil types, slopes and plant growth.

Geographically, the model included data not only about the sea itself, but also about the surrounding watersheds, streams that flow into the lake, and the land area that flows into these streams.

Model data was difficult to obtain because it is a transboundary basin located on the US-Mexico border between California and Baja and California’s Del Norte County. However, using publicly available data and data mining techniques, UCLA scientists were able to model the long-term dynamics of the water balance and identify the decline in the flow of the Colorado River as the main cause of the reduction in the Salton Sea and the decrease in the flow of the lake’s tributaries.

“It’s not entirely clear whether the shrinking of the Colorado River is due to global warming draining the river, lower levels of water distribution in California, or both,” Acero Triana said.

Despite this ongoing uncertainty, the team says the study should send a signal to water management agencies and lawmakers that the Salton Sea drainage basin should be considered part of the Colorado River basin.

“The sea is generally considered to be an independent system, and a watershed-centred approach, taking into account surface and groundwater resources, is needed to find a solution. With the growing environmental risks associated with the drying of the sea, all parties must work together to reduce these risks” Ajami said.

This result and the methods used to obtain it have now been published in the journal Water Resources Research.

Source: Science Daily.

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