Commentary: The next big air pollution threat in the San Joaquin Valley: dust from fallow farmland

This comment was posted in The Fresno Bee July 22, 2022.

The San Joaquin Valley has faced air quality issues for decades. It is a major transportation artery and has always been prone to particulate and dust problems which are often aggravated by high winds and pollution-trapping topography.

Over the past few decades, particulate matter concentrations have declined, although recent wildfires have reversed some gains. But the valley now faces another threat to air quality: the impending decommissioning of hundreds of thousands of acres of irrigated farmland to ensure groundwater sustainability. It is imperative that regional, state, and federal actors take proactive steps to address these risks early on.

The dangers of dust

Farming and wind erosion are two of the main sources of dust in the valley. We predict that over 500,000 acres of farmland may need to be taken out of production over the next two decades to help balance groundwater basins under the Sustainable Groundwater Management Act 2014 (SGMA ). This is a huge area of ​​land, and without careful management, widespread fallowing could cause an increase in windblown dust.

The threats from dust are real. Both fine and coarse particles can cause acute and chronic respiratory problems, as well as cardiovascular complications. Fine particulate exposure has also been linked to dementia, reduced labor force participation and productivity, and developmental complications in unborn children, infants, and children.

To add to this toxic cocktail, Valley fever – which derives from a fungus that grows in the soil in the southwest – is on the rise and transmitted by windblown dust.

The valley’s poor air quality has had serious consequences for human health, and the economic impacts are startling – one estimate assesses the valley-wide costs of air quality-related health impacts. air at $3 billion a year. Emerging impacts of set-aside would likely be borne first and foremost by low-income rural communities.

It is important for the region to get ahead of this problem. Our new research explores how proactive management to reduce dust emissions can bring big benefits. Smart investments in monitoring to better understand rural dust can help guide future decision-making. Regional, state, and federal agencies should clarify the roles GSAs and landowners should play in dust mitigation, and identify new and existing sources of funding to support additional and ongoing mitigation efforts.

Ways to reduce risk

These approaches will need to be adapted to local conditions. The net effect of land transitioning from active agriculture to fallow appears to depend on the crop grown, the level of land disturbance from inactivity, and the time of year. Risks can be minimized by certain on-farm practices and prior identification of priority mitigation areas.

Maintaining ground cover is one of the easiest and most cost-effective ways to control dust from unused landscapes. Establishing this cover without irrigation, however, is a challenge. In a related study, we show that water-constrained agriculture, with a small amount of irrigation to establish cover, could provide a way forward. Grazing is often part of successful vegetation management and can provide economic returns from these lands, but if poorly managed it can disturb soils and increase dust hazard. Coordinated management of these lands to establish robust ground cover – or other dust control measures – will be paramount.

Dust control projects are already underway on transition and fallow lands across the West. One lesson is that reliable funding is needed to establish proactive dust management programs in the San Joaquin Valley. Groundwater sustainability agencies can provide local funding, the regional air district can administer state funding, and federal support can come from existing conservation programs and environmental incentives.

Residents of the San Joaquin Valley have endured some of the country’s worst air quality in decades. A combination of wildfires and newly set-aside farmland could threaten recent significant progress. But with foresight and planning, the region could take key steps to minimize these risks and ensure a healthier environment in a more sustainable valley.

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