A Drying Salton Sea Pollutes Neighboring Communities

Research Finds Higher Particulate Pollution After Water Diverted to San Diego

drone image of Salton Sea waters going up to dry lakebed with mountains in distance
Dust from the Salton Sea playa is impacting nearby communities following water diversions to San Diego. (Getty)

When desert winds stir up dust from the Salton Sea鈥檚 exposed lakebed, nearby communities suffer from increased air pollution. The deterioration coincides with reduced flows into California鈥檚 largest lake, in the American Journal of Agricultural Economics finds. 

Disadvantaged communities have been affected more than others in the areas near the Salton Sea, which has been shrinking for years, said the paper鈥檚 co-leading author Eric Edwards. He is an assistant professor of agricultural economics at University of California, Davis, who did the research while at North Carolina State University. 

鈥淲e have a dusty area, and any time there is wind, it鈥檚 going to pick up dust and move it around,鈥 Edwards said. 鈥淲e think this new dust is increasing the amount of pollution faced by disadvantaged communities in the region surrounding the lake.鈥


Salton Sea lakebed
The dry lakebed of the Salton Sea. (Emily Dooley/swag外流)

An overflowing river

The Salton Sea formed in 1905 after the Colorado River overflowed its banks and the floodwaters settled into what was known as the Salton Sink. It was primarily fed by water runoff from agricultural operations for almost a century. As the southern part of California struggled to meet growing water demand, the Imperial Irrigation District agreed to send water to San Diego for urban use. 

Imperial, which supplies water to vast desert farms as well as seven towns and two special districts, is the largest user of Colorado River water. The agreement with San Diego required agricultural water users to increase efficiency and reduce their water consumption, which reduced water running into the Salton Sea, Edwards said. 

The reductions increased the lake鈥檚 salt content, which is higher than in the Pacific Ocean. This also harmed wildlife habitats and created localized air pollution. The area is the subject of many environmental restoration projects. 

Studying implications

Edwards and others used a particle transport model to study the effects of changing water diversions on particulate pollution.

They found that the paths of fine particulate matter 鈥 which can cause asthma, heart and respiratory issues when inhaled 鈥 were associated with higher air pollution readings after Imperial began reducing runoff water to the Salton Sea around 2011 in order to transfer it to San Diego, a practice that continues today. 

Researchers modeled lakebed exposure by dividing the lake鈥檚 shoreline into 1-square-kilometer grids and collected air pollution data daily for over 20 years, from 1998 to 2018. They added data about the exposed lakebed, or playa, and used a sophisticated physics model called HYSPLIT to factor in wind levels and particle size to track the movement of dust over time. State health screening information available by ZIP code added more to the story by pinpointing disadvantaged areas, asthma rates and other vulnerabilities. 

A map of Salton Sea dust emissions
A map shows the path of dust emissions emanating from one point of Salton Sea playa. (Eric Edwards/ swag外流)

Lake levels were higher in 1998 before the transfers, so the change was not evident until later years, when the lakebed became more exposed. 

鈥淲e show that during that post-2011, there is an increase in particles going through disadvantaged communities relative to non-disadvantaged communities, which are farther away from the sea,鈥 Edwards said.

In the paper, the pollution paths are depicted on a map of the state. The Salton Sea is marked with a black dot, and red lines radiate from there to distances of 100 miles or more. 

鈥淔rom every exposed grid cell you have these paths predicting where the particles are going based on physics,鈥 Edwards said. 鈥淭hat鈥檚 the path of emissions.鈥

Prior research suggests that dust particles from newly exposed playa are more susceptible to wind erosion. 

鈥淭here鈥檚 lots of evidence that playa is particularly emissive in terms of dust,鈥 Edwards said. 鈥淚f it鈥檚 dry, those particles get picked up readily by the wind and create dust 鈥 and at rates higher than areas that have been exposed to the wind over long periods of time.鈥 

Informing decision makers

Edwards said policymakers and regulators should consider the health and environmental impacts of water diversions in their decision making.

鈥淭he drying up of the Salton Sea has serious health consequences that have generally fallen on more disadvantaged populations, who may not be well equipped to advocate for policies that improve their health,鈥 he said. 鈥淧olicymakers need to think about how to facilitate the movement of water via market transactions, which are essential, while also accounting for potential negative effects on the environment.鈥

Ryan Abman from San Diego State University and Dana Hernandez-Cortes from Arizona State University contributed equally with Edwards to the research and journal article. 

The U.S. Department of Agriculture鈥檚 National Institute of Food and Agriculture supported this research. 

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Media Resources

Media Contacts:

  • Eric Edwards, swag外流 Department of Agricultural and Resource Economics, ecedwar@ucdavis.edu
  • Kat Kerlin, swag外流 News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu 
  • Susanne Clara Bard, San Diego State University Strategic Communications and Public Affairs, 202-441-8976, sbard@sdsu.edu
  • Emily C. Dooley, swag外流 College of Agricultural and Environmental Sciences, 530-650-6807, ecdooley@ucdavis.edu 

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