Conserve groundwater. Fallow farmland. Increase dust?

A new study warns that California’s groundwater regulations could create more dust, worsening already poor air quality.

For a century, California’s San Joaquin Valley has been known as “the food basket of the world.” The 27,500-square mile region currently produces over $34 billion worth of food each year, a productivity made possible only by its large-scale irrigation projects and unrestrained groundwater pumping. In 2015, however, California passed the Sustainable Groundwater Management Act (SGMA), making it the last Western state to regulate its groundwater — and bringing the San Joaquin Valley into compliance with the law will require retiring over 500,000 acres of its farmland in the next 20 years.


While SGMA’s regulations are for the greater good — achieving sustainable water use in an increasingly unpredictable climate — they are likely to have negative effects on the ground. According to Land Transitions and Dust in the San Joaquin Valley, a July 25 report by the nonprofit, nonpartisan think tank Public Policy Institute of California, fallowing those 500,000 acres is likely to create significant amounts of dust in a region already has the country’s worst air quality. If the land is simply taken out of production and left unused, SGMA’s climate adaptation goals could worsen existing environmental injustices in the area’s frontline communities.

The San Joaquin Valley, which is home to 4.3 million people, already has some of the highest ozone levels in the country. The American Lung Association ranks three of its metro areas — Bakersfield, Visalia and Fresno-Madera-Hanford — as the U.S. cities with the highest levels of particulate matter. Catherine Garoupa White, executive director of the Central Valley Air Quality Coalition, says that the pollution is caused by a combination of industrial agriculture, pesticides, freight traffic and oil extraction. The valley’s geography exacerbates the problem by trapping the polluted air and holding it close to ground level.

Near Fresno, California, farmers create huge dust clouds while turning the dry remains of a cotton field in 2002. Fallowed land is often tilled to prevent weed growth, a practice that further increases dust.
Spencer Weiner/Los Angeles Times via Getty Images

The increased dust will only add to the problems facing communities that have long suffered disproportionately from environmental injustices, such as exposure to pesticides and oil and gas wells. “We are one of the poorest and most unequal regions in the United States,” said Garoupa White. “Neighborhoods where (pollutant) sources are concentrated are mainly communities of color, with lower incomes and other social vulnerabilities.”

Andrew Ayres, lead author of the land transitions report, said that the prospect of increased particulate matter is particularly worrisome because it threatens recent improvements to air quality. During the last 20 years, significant progress had been made in cleaning the valley’s air, mostly by addressing the dust from active agricultural operations. Nearly $13 million was spent on replacing outdated nut harvesters, which blew dirt and debris off nuts in large air plumes, for example. Now, if retired agricultural lands aren’t proactively managed to control dust, said Ayres, “those air quality gains could be undone.”

To understand the impacts of taking land out of production, Ayres and the report’s other authors used new, satellite-based measurements to study the relationship between land cover and air particulates. As a general rule, he said, fallowing land increases dust, though a lot depends on the variety of the crops and the time of year. “We don’t know a lot about rural dust. We don’t measure it well,” he said, adding that there are only two dust monitors between the cities of Bakersfield and Fresno, which are over 100 miles apart.

The respiratory and other health effects of poorer air quality will be felt most acutely by the San Joaquin Valley's frontline communities, both urban and rural — particularly farmworkers, incarcerated individuals and low-income communities of color. Kamryn Kubose, of Central Valley Young Environmental Advocates, said that the possibility of increased dust is very troubling given the region’s existing air-quality issues, and the fact that the communities that are most affected often lack the resources needed to address the problem. The valley also suffers from a shortage of doctors, nurses and nurse practitioners: There are only 47 primary care providers per 100,000 people, compared to the national average of 92.

“Mechanically, as the valley gets hotter and drier, soils will dry, and dust problems will only get worse.”

Dust settles over a tumbleweed-covered fallow field near Visalia, California. The health effects of poorer air quality will be felt most acutely by farmworkers, incarcerated individuals and low-income communities of color.
David McNew/Getty Images

To make matters worse, Central Valley dust can carry the fungal spores that cause a respiratory condition known as Valley fever, which disproportionately affects Black, Hispanic and Filipino communities and is particularly dangerous to the elderly and people with weakened immune systems. Because incarcerated Californians are disproportionately Black, Valley fever has already created a public health crisis in the area’s many prisons.

Increasing dust is not just caused by SGMA regulations. “Everything is going to be affected by climate change going forward,” said Ayres. “Mechanically, as the valley gets hotter and drier, soils will dry, and dust problems will only get worse.” He added that wildfire smoke and “unpredictable” fallowing due to drought are also affecting the valley's air. (Already, around 530,000 acres have been taken out of production due to drought.)

As High Country News previously reported, Central Valley residents and farmers are starting to explore new land-use options for retired farmland. Currently, fallowed land is often tilled to prevent weed growth, a practice that further increases dust. Ayres said that the simplest, most cost-effective way to control dust is to maintain some vegetative cover — as long as it doesn’t require too much water. “We need to focus on crops that are less water-intensive, and promote agroecology,” said Kubose, emphasizing that the solutions will be different across the valley. “It’s not a one-size-fits-all.”

Other options include covering the ground with something too heavy to be picked up by the wind, such as gravel or almond hulls, a waste product from local agriculture.

While the new SGMA regulations make these questions particularly urgent in the Central Valley, Jaymin Kwon, one of Ayres’ co-authors, said that the entire Western U.S. faces similar problems owing to water shortages. “When open pumping gets reined in in Arizona,” Kwon said, “they’re going to start to ask these questions.”

Caroline Tracey is the Climate Justice Fellow at High Country News. Email her at [email protected] or submit a letter to the editor. See our letters to the editor policy.