As the water pulls back from long-time shorelines along California’s Salton Sea, officials are working to keep dust from the exposed lake bottom out of the air.
Bruce Wilcox of the California Resources Agency looked out at what is now the new normal on the 35-mile-long lake’s southeastern shore.
“Fifteen years ago there was water right where we’re standing and it’s just receded that much,” Wilcox said as he stood on a spur of land that used to be part of a boat launch.
He points out that as the lake level drops, more lakebed is exposed.
Dust is a major concern
“And it will continue to recede. It’s very flat. And so for every vertical foot of drop there is several thousand feet of horizontal exposure,” Wilcox said.
The sandy playa that used to be underwater is now being baked by the sun and blown around by the winds that frequently scour the desert floor here. That concerns Wilcox. The dust is tiny and can easily get airborne. That is a public health crisis for a region already suffering from some of California’s highest asthma rates.
“Particulate matter — 10 microns — very, very small dust, but inhaled it is a health hazard all by itself,” Wilcox said. “But also probably adhering to that particulate matter here are toxic material of one kind or another.”
For decades the lake has been fed with pesticide and salt-laden water from nearby farm fields. The Salton Sea also takes in an unhealthy dose of sewage and toxic material from the New River which flows north from Mexicali. Those contaminants didn’t use to be a concern, because they were contained by the lake. Not anymore.
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California’s 10-year management plan involves flooding more than 20,000 newly exposed acres of lakebed to control the potentially toxic dust and create wildlife habitat.
But the state only has half of the money needed for the effort, and the first flooding project, at Red Hill Bay, is running two years behind schedule.
Trenching could help slow wind
Jessica Humes, of the Imperial Irrigation District, walked along a deep tractor-cut ditch just south of the Alamo River.
There are rows and rows of the ditches next to each other on this plot of land that used to be lakebed.
“Although rain is really nice for the overall desert area, on the playa it brings these salts up and as soon as they dry and we get a nice good wind from the west they will just blow. And it is almost whiteout conditions just from the dust,” Humes said.
So these ditches, which run north to south, will help slow down westerly winds as they pass across the trenches.
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“The logic here is that if you create this furrow, the winds come mostly from the west to this area, so they’ll bring any salt, dust particles in through the array and with each little hump they have to go over they drop out some of the dust particles.”
Winds that blow at 25 miles per hour, 10 feet above the ground, only go half as fast at the surface where it has to travel over the terraces cut in the dirt.
“This is not nearly as dusty as a playa to the south, which has no projects on it,” Humes said.
This dust control project won’t work everywhere.
The lakebed needs to be made at least partly of clay, the dust is reduced only when winds come from the west, and researchers do not know if the dust control projects are effective when there are stronger winds.
And there are frequently stronger winds in the valley. But Imperial Irrigation District monitoring proves the project can be part of the solution.
More needs to be done
“There are three times the state’s childhood asthma rates in this area. It's serious,” said Robert Schettler, communications officer at the Imperial Irrigation District.
Habitat ponds designed to cover the exposed playa need to be built soon, but that takes money. California currently only has $200 million of the estimated $480 million needed to build habitat ponds that also keep the dust in check.
“The Salton Sea can be sustainable, yet it needs to be a smaller sea. So we would like to work with our partners on that, and how that comes about, that remains to be seen,” Schettler said.
The district is trying to leverage its position as a senior rights holder of Colorado River Water to get federal matching funds — $200 million from the U.S. Farm bill.
That could double the amount of money the state has available for the project and it could get more effective dust control measures built.
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