New Study: Dramatic Growth of Manure Digesters on Wisconsin Mega Dairies Brings More Cows, More Pollution



Expert contact:
Molly Armus
Friends of the Earth

Media contact:
Haven Bourque
Friends of the Earth

Data reveal 58% increase in herd sizes on farms with digesters in Kewaunee County

Washington, D.C.—Today, Friends of the Earth U.S. and Socially Responsible Agriculture Project released a new report, Making a Bad Situation Worse: Manure Digesters at Mega Dairies in Wisconsin. The report documents the harmful community impacts associated with the rapid growth in manure digesters in Kewaunee County, where cows outnumber residents 5 to 1. Industrial animal agriculture operations are a major driver of the climate crisis—accounting for 36% of total U.S. methane emissions —and digesters are employed to capture those emissions.

Based on government data and interviews with residents, the report finds that all dairies with digesters in the county significantly increased their herd sizes, generating more air and water pollution and more enteric methane emissions. This is consistent with Friends of the Earth U.S. and Socially Responsible Agriculture Project’s recent research, which finds that across the country, dairy operations with manure digesters grew 3.7% year-over-year, 24 times the growth rate for overall dairy herd sizes.

“Water contamination, including elevated nitrate levels in water supplies, is a major concern in Kewaunee County. Paying industrial livestock polluters to generate methane gas will make the urgent public health threat these operations pose to communities even worse.” said Molly Armus, animal agriculture policy program manager, Friends of the Earth U.S. “Anaerobic digesters are a greenwashed corporate handout that encourage factory farm expansion, contribute to industry consolidation, and exacerbate pollution.”

Subsidies for digesters and policies like the federal Renewable Fuel Standard (RFS) and California’s Low Carbon Fuel Standard (LCFS) are cornerstones of government efforts to curb industrial animal agriculture’s climate-warming methane emissions. Unfortunately, they create perverse incentives for livestock operations to maximize methane yield to receive lucrative payments for biogas. This builds on FOE and SRAP’s research, which revealed that manure digesters yield far lower methane emission reductions than estimated by the U.S. government and that these reductions are highly variable and uncertain due to a lack of monitoring.

In addition to exponential herd size growth and continued pollution from CAFOs, the report found dangerous spills, increased ammonia emissions, and damage to local infrastructure have all accompanied the proliferation of manure digesters.

“Having spent a decade helping Wisconsin communities facing industrial livestock operations, I can say from experience that biodigesters do nothing to address the public health and environmental damages that these facilities have caused across my state,” said Mary Dougherty, senior regional representative, Socially Responsible Agriculture Project. “In fact, digesters make a bad problem worse while diverting limited public funding from true climate solutions.”

Key findings from the report include:

  • Increased herd sizes. Herd sizes at Kewaunee County CAFOs with digesters grew by 58%, an annual year-over-year herd size increase of 5.2%, 52 times the growth rate for overall dairy herd sizes. Previous research found that across Wisconsin, CAFOs with digesters grew by 2.4% year-over-year, while industrial livestock operations in the state without a digester had an annual year-over-year herd size increase of just 0.1%.
  • Anaerobic digester growth. 28% of Kewaunee County CAFOs now use anaerobic digesters to produce factory farm gas, including one of the largest CAFOs in Wisconsin.
  • Repeat violations. All five Kewaunee County CAFOs with digesters have experienced at least one spill since digester installation, including one operation that reported 23 spills since installing a digester in 2009. All of the Kewaunee County CAFOs with digesters also received one or more citations for nutrient management plan implementation violations after installing a digester.

The Kewaunee County residents interviewed for the report see manure digesters as a perpetuation of the problem rather than a solution. Instead of more digesters, they want stronger enforcement of environmental protection laws, more support for sustainable, regenerative agriculture and truly renewable energy, and an end to incentives for manure biogas.

The report includes several policy recommendations, including redirecting public resources to more effective methane reduction solutions that do not exacerbate environmental pollution and industry consolidation; regulating waste from CAFOs and digesters; strengthening enforcement of nutrient management plan violations; and prohibiting new construction and expansion of large CAFOs in Wisconsin.

About SRAP
For more than 20 years, SRAP has served as a mobilizing force to help communities protect themselves from the damages caused by industrial livestock operations and to advocate for a food system built on regenerative practices, justice, democracy, and resilience. Learn more at

About FOE
Friends of the Earth fights to create a more healthy and just world. Our current campaigns focus on promoting clean energy and solutions to climate change, ensuring the food we eat and products we use are safe and sustainable, and protecting marine ecosystems and the people who live and work near them.