What are CAFOs?

The Coalition to End Factory Farming has identified 21 large Concentrated Animal Feeding Operations (CAFOs) in Sonoma County, which are listed in the “Large CAFOs” section below. Continue reading to understand how CAFOs are defined.

Defining AFOs and CAFOs

To be a Concentrated Animal Feeding Operation (CAFO), a facility must first meet the EPA’s definition of an Animal Feeding Operation (AFO). According to the EPA:
“Animal feeding operation (“AFO”) means a lot or facility (other than an aquatic animal production facility) where the following conditions are met:

  • Animals (other than aquatic animals) have been, are, or will be stabled or confined and fed or maintained for a total of 45 days or more in any 12-month period, and

  • Crops, vegetation, forage growth, or post-harvest residues are not sustained in the normal growing season over any portion of the lot or facility.”

Source: Title 40 Code of Federal Regulations §122.23(b)(1)

An AFO becomes a CAFO when it meets the regulatory definition of a large CAFO (confining a certain number of animals) or of a medium CAFO (confining a smaller number of animals but also discharging waste into surface water), or when it is deemed a major polluter by regulatory authorities on a case-by-case basis.

Source: EPA.Gov

Small and Medium CAFOs

Any CAFO in the US that discharges waste to surface water is required to obtain a National Pollutant Discharge Elimination System (NPDES) permit from the EPA. Because the definition of a medium CAFO includes discharge of waste to surface water, any medium CAFO would be required to have an NPDES permit. The California State Water Resource Control Board’s NPDES Permit Facility Search system shows that there are no CAFOs in the county permitted to discharge waste, meaning there are no medium CAFOs in Sonoma County. If any AFO within the medium size range was discharging waste into surface water without an NPDES permit, that would already be a violation of either the North Coast or SF Bay Regional Water Quality Control Board rules and EPA guidelines. 

Any AFO can be designated a CAFO by regulatory authorities on a one-off basis, if it is found to be a major risk to the environment, regardless of the number of animals it confines. This is extremely rare. Becky Mitschele, Acting Watersheds Manager at US EPA Region 9, which includes California, said she was only aware of small CAFO designation happening a couple times in the Midwest, and that there are no small CAFOs in Sonoma County.

Given our research and communication with local and federal regulatory agencies, it is our best understanding that there are no small or medium CAFOs in Sonoma County. 

Large CAFOs

While our best understanding is that there are no small or medium CAFOs in Sonoma County, research shows that there are multiple facilities that meet the regulatory definition of large CAFOs. Large CAFOs are defined as any AFO that confines more than a certain number of animals, with that number depending on the species, the product being produced, and whether the facility uses a solid or liquid manure handling system.

Through extensive open source research, we have identified 21 large CAFOs in Sonoma County, which are listed in the table below. This list aims to be overinclusive; we believe it is highly unlikely that large CAFOs are missing from the list based on our review of approximately 100 of the largest animal farms in Sonoma County, obtained by public records and thorough analysis of satellite imagery. All data listed is a best estimate based on available information.

CAFO Research Methodology

The above research was conducted by volunteers based on the best available evidence that could be located. Whenever two sources provided contradicting estimates of animal populations at a facility, we used the higher number sources in order to lean toward over-inclusion of facilities as CAFOs, so that the possible impacts of the CAFO prohibition are not underestimated. It is possible that some population sources we used count animals not relevant to the CAFO number threshold, such as immature heifers on a dairy farm. It should be possible for county officials to make more accurate assessments based on information not available to the public. 

The majority of dairy farms were able to be assessed based on data from regional water boards.

Some poultry/egg facilities were able to be assessed based on USDA reports from the 2023-2024 HPAI outbreaks.

The remainder of poultry/egg facility populations were estimated based on a projected average of birds per square foot of barn space, generated by calculating the average for known facilities of the same type, and owner when possible.