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Press Release

J.R. Simplot Company to Reduce Emissions at Sulfuric Acid Plants in Three States

For Immediate Release
Office of Public Affairs
Estimated $42 Million Settlement Resolves Clean Air Act Violations at Plants in California, Idaho and Wyoming

The Department of Justice and the Environmental Protection Agency (EPA) today announced a settlement with the J.R. Simplot Company that resolves alleged Clean Air Act violations related to modifications made at Simplot’s five sulfuric acid plants near Lathrop, California, Pocatello, Idaho, and Rock Springs, Wyoming. Under the settlement, Simplot will spend an estimated $42 million on pollution controls that will significantly cut sulfur dioxide (SO2) emissions at all five plants and fund a wood stove replacement project in the area surrounding the Lathrop plant.  Simplot’s Pocatello plant will receive $15 million in pollution control upgrades.

Once fully implemented, the settlement will reduce SO2 emissions from Simplot’s five sulfuric acid plants by more than 50 percent for approximately 2,540 tons per year of reductions (825 tons per year of which will be at the Pocatello plant).  Simplot will implement a plan to monitor SO2 emissions continuously at all five plants and pay an $899,000 civil penalty. Additionally, Simplot will spend $200,000 on a wood stove replacement mitigation project in the San Joaquin Valley, the location of Simplot’s Lathrop facility, to reduce emissions of fine particulate matter (PM2.5), as well as emissions of volatile organic compounds (VOCs), carbon monoxide (CO) and hazardous air pollutants (HAPs).

“Under this proposed settlement, Simplot must upgrade its pollution controls and cut harmful air pollution in half at its acid plants, bringing lasting benefits to communities in three states,” said Principal Deputy Assistant Attorney General Sam Hirsch for the Justice Department’s Environment and Natural Resources Division.  “The Justice Department will continue to vigorously enforce the Clean Air Act, which protects public health and air quality for Americans each and every day.”

“This settlement helps address public health risks for local communities in California, Idaho and Wyoming, and furthers EPA’s commitment to reduce harmful air pollution from the largest sources,” said Cynthia Giles, assistant administrator for EPA’s Office of Enforcement and Compliance Assurance. “The system-wide pollution controls Simplot will install will significantly reduce sulfur dioxide emissions, which can cause serious respiratory problems and exacerbate asthma.”

“The people of southeastern Idaho will receive significant benefits from the cleaner air and better health produced by this settlement,” said U.S. Attorney Wendy J. Olson for the District of Idaho.  “I am pleased that the federal government and the J.R. Simplot Company are able to reach this agreement that serves Idahoans so well.”

The Department of Justice and EPA alleged that Simplot made modifications at its five sulfuric acid plants without applying for or obtaining the necessary Clean Air Act permits and obtaining “best available control technology” limits for SO2, as well as for sulfuric acid mist and PM2.5 at one of the sulfuric acid plants in Pocatello.

Short-term exposures to SO2 can lead to serious respiratory problems, including constriction of airways in the lungs and increased asthma symptoms.  Additionally, SO2 is a precursor to the formation of PM2.5, which causes a wide variety of health and environmental impacts, including asthma attacks, reduced lung function and aggravation of existing heart disease. Simplot’s Lathrop sulfuric acid plant is located in the San Joaquin Valley in California, which is currently classified as nonattainment for the PM2.5 National Ambient Air Quality Standards and has some of the most difficult challenges meeting those standards in the country.  SO2 is a precursor for the formation of fine particulates, so both the SO2 emission reductions from Simplot’s Lathrop plant and the wood stove replacement mitigation project will help reduce PM2.5 emissions in the San Joaquin Valley. 

The state of Idaho on behalf of its Department of Environmental Quality and the San Joaquin Valley Unified Air Pollution Control District are parties to the proposed settlement.

This settlement is part of EPA’s national enforcement initiative to control harmful emissions from large sources of pollution, which includes acid plants, under the Clean Air Act’s Prevention of Significant Deterioration requirements.  The emission rates secured in this settlement will result in the best-controlled, system-wide emissions achieved in any sulfuric acid plant settlement to-date.

The consent decree formalizing the settlement was lodged with the U.S. District Court in the District of Idaho and is subject to a 30-day public comment period and final court approval. The proposed consent decree can be viewed at:

Updated April 5, 2024

Press Release Number: 15-1481