Home to around a third of California’s dairy cows and 295 concentrated animal feeding operations (CAFOs), Tulare County hosts 49 anaerobic digesters — approximately 11% of all manure digesters in the United States. Anaerobic digesters capture methane emissions from animal waste to produce so-called manure biogas. Because biogas can be converted into heat, electricity, and fuel, these digesters have been promoted as a climate solution. However, as this report investigates, they’re intensifying pollution burdens in vulnerable communities instead.

The demographics of Tulare County highlight the environmental justice issues. The county is predominantly Hispanic/Latinx (67%), with half of residents speaking a language other than English at home and 22% being foreign-born. Economic disparities are stark — the median household income is $64,474 compared to California’s $91,905, and about 18% of residents live in poverty. Research shows that CAFOs are deliberately sited in such vulnerable communities, with people of color being roughly 1.3 times more likely to live within three miles of a large dairy CAFO in California.

Government policies have created a complex web of incentives driving digester expansion. The federal Renewable Fuel Standard (RFS) requires renewable fuels be mixed with traditional petroleum fuels, creating a guaranteed market. California’s Low Carbon Fuel Standard (LCFS) further drives demand by awarding credits to lower-carbon fuels. Currently, producers can earn $3.09 per gallon through RFS and $65 to $67 per metric ton through LCFS. These incentives create perverse effects. Modeling shows that farms with 100 or fewer cows cannot profit from LCFS, while those with 15,000 cows can make 39 cents per gallon of milk. About 43% of Tulare County digesters benefit from both programs. The largest cluster, Calgren Dairy Fuels LLC, operates 20 digesters (40% of the county total) and participates in both programs.

Local policies enable expansion by allowing dairies to add digesters without individual environmental review under the California Environmental Quality Act. Public engagement is severely limited. Meetings are held during work hours 30 miles away from impacted communities, with minimal translation services despite 50% of residents speaking a language other than English at home.

Oversight is notably lacking. The California Water Board inspected just 10% of Central Valley facilities between 2022 and 2023. Since 2010, 95% of water violations at Tulare County dairy operations have resulted in informal enforcement actions only, despite 70% being classified as posing moderate threats to water quality. Reporting basic data like herd sizes is inconsistent and unverified across different agencies.

Recent research casts doubt on digesters’ climate benefits. A 2023 study using mobile optical sensing found facilities with digesters didn’t emit significantly less methane than those without, and measured emissions were 60% higher than reported in state inventories. According to Inside Climate News, cows nationwide emitted more than twice as much methane in 2020 as all oil and gas wells.

At the same time, reform efforts have faced significant resistance. A 2022 petition to amend LCFS was rejected by the California Air Resources Board. Two reform bills in 2024, Senate Bill 709 and Assembly Bill 2870, which would have improved transparency and prevented herd size expansion, were blocked early in the legislative session.

The health impacts on Tulare County residents are severe and compounding. The county’s CAFOs with digesters produce over seven million tons of manure annually — 3.5 times California’s human waste production. Digester operations increase ammonia emissions by up to 81%, while burning biogas onsite produces high levels of pollutants like nitrogen oxides, sulfur oxides, and volatile organic compounds. In fact, biogas is considered 10 times more toxic to human health than natural gas. Water quality is also at risk, as anaerobic digestion concentrates nutrients like nitrogen and phosphorus, which can leach into waterways. Local residents advocate for redirecting resources toward effective methane reduction solutions and increased industry oversight.

For animal advocates, this case study provides compelling evidence that technological “solutions” like digesters often perpetuate and worsen industrial agriculture’s impacts while providing cover for expansion. The experiences of Tulare County demonstrate how environmental justice, public health, and animal welfare concerns intersect. Advocates can use this evidence to challenge the narrative that digesters represent meaningful climate action, and instead push for policies that support a transition away from industrial animal agriculture while protecting vulnerable communities.