Crying Over Spilt Milk:

Controlling H5N1 in California Dairies: Student Policy Practicum Findings

Edited by Avery Bick and Jordan Stock

Original Report by Astrid Elliott, Chloe Haydel Brown, Coleman Sherry, Jordan Stock

Introduction

California has over 1.7 million dairy cows and, as the top milk production state, produces twenty percent of the Nation’s milk. Ninety percent of California’s cows are raised in close-quarters on large dairies concentrated on just 11 percent of California’s land area in the state’s Central Valley.¹ As the cows are milked and managed by thousands of farmworkers, this large number and density of dairies facilitates disease spread and risk of cow-to-human disease mutation.

In March 2024, when the first cases of Highly Pathogenic Avian Influenza Type A (H5N1) were detected in dairy cattle in Texas and Kansas, California dairies were particularly vulnerable.² Over the next ten months, at least 766 dairies—more than seventy percent of California’s herds—were infected.³ By October 2024, the first human case of H5N1 in a California farmworker was confirmed. Generally, human infections are mild and only occur when someone is in close, direct contact with an infected animal. However, the virus’s continued spread in cattle dramatically increases its evolutionary opportunity, increasing the likelihood of a mutation enabling human-to-human transmission.⁴

In response to the rise in zoonotic disease threats, animal welfare concerns, and California’s Central Valley community member alarm, students in the Building A Sustainable, Transparent, and Humane Food System Policy Practicum⁵ interviewed community members, California’s State Veterinarian, a small dairy farmer, several agency officials, and scientists. Their work culminated in a report that outlines the regulatory systems that manage zoonotic risk and how these systems operated during the H5N1outbreak in California dairies.

Two consistent themes across the report are a) that while many government agencies have broad authority to act, this authority is largely discretionary and often underused; and b) where mandates do exist, there is limited oversight and enforcement. The reasons behind this limited agency action appear to largely stem from conflicting agency priorities, underfunding, and understaffing.

While the student report provides several policy recommendations ranging from the pragmatic to the ideal, this post highlights four:

• Provide training on reporting violations through anonymous tiplines

• Thoroughly translate all agency public health information

• Clarify and mandate specific low-cost livestock carcass management protocols

• Require biosecurity plan submission to the California Department of Public Health or another relevant agency

Provide training on reporting violations through anonymous tiplines

Despite having biosecurity plans, many dairy workers report having minimal on-farm safety measures. Policy violation persistence appears largely linked to a) employee fear of retaliation if they speak up and b) lack of Cal/OSHA enforcement staff visiting farms to check compliance. One way to assist limited enforcement staff in identifying noncompliant farms and address employee retaliation fears, is to increase multilingual anonymous tipline education.⁶

Currently, Cal/OSHA operates tiplines and receives both “Safety and Health Complaints” and “Whistleblower Complaints.” These tips can be made over the phone, online, in person, in any language, by a third party, on a worker’s behalf, and often anonymously. Yet, Cal/OSHA reported that as of March 31, 2025 they had not received any H5N1-related tips. A Cal/OSHA official explained that tips stating the specific violated regulation are more likely to lead to official inspection and enforcement.⁷

In the H5N1 context, educating farmworker communities about Section 5199.1 (mandatory workplace requirements) would likely increase both farm compliance with, and agency oversight of, a farm’s biosecurity plan. Overall, community groups, if not local governments, could provide more information about the existence of, and how to optimally use, anonymous tiplines to help focus limited Cal/OSHA resources.⁸

Thoroughly translate all public health information

An effective response to a zoonotic outbreak like H5N1 requires considerable community outreach and education about risks, precautions, and one’s rights. Accordingly, the California Department of Public Health (CDPH) launched several public health campaigns regarding H5N1. CDPH provides information about transmission and mitigating spread, how to protect oneself, and how to get tested. However, the majority of these campaigns and resources are disseminated online.

This approach presumes that users (1) are aware that such information exists online, (2) have reliable internet access and can navigate CDPH websites, and (3) can understand and interpret the materials. Unfortunately, these presumptions do not seem to be universally true. Central Valley dairy workers report that most of their H5N1 information has come through family members with first hand experiences, farmer WhatsApp groups, social media accounts, and the radio. Additionally, there have been discrepancies between CDPH’s English and Spanish H5N1 fliers.⁹ Specifically, some Spanish fliers lack information about workers’ workplace rights, paid sick-leave requirements, and workers’ compensation.

To ensure that official materials and public health guidance is disseminated effectively to relevant populations, CDPH may consider how to a) expand where and how they disseminate their H5N1 information to include the most common information avenues for high-risk communities and b) ensure that the same information is shared and translated across all relevant languages.

Clarify and mandate specific low-cost livestock carcass management protocols

While the average H5N1 dairy cow mortality rate is unknown, the latest estimates suggest it reached over 15% in infected Central Valley herds,¹⁰ likely resulting in well over 50,000 deceased cows.¹¹ However, government guidance or regulation regarding deceased cattle management is minimal.¹² At the federal level, the Environmental Protection Agency, Centers for Disease Control and Prevention, and Animal and Plant Health Inspection Service offer guidance,¹³ but defer to state and regional governments for regulation and enforcement.¹⁴ At the state level, the most information appears to come from the 2006 Emergency Animal Disposal Guidelines, which are just that: guidelines.¹⁵

The California Department of Food and Agriculture’s (CDFA) Animal Health Branch (AHB) explains that AHB District offices have Regional Carcass Disposal Plans that, “addresses a number of emergency scenarios and animal mortality disposal options,” and that “coordination with county officials in the affected areas is a key factor in determining available emergency carcass disposal options.” This guidance implies that approved animal disposal methods are largely left to regional decision makers. Unfortunately, aside from office and fax numbers, there is little online AHB regional information for California’s top dairy counties.

AHB’s July 2021 newsletter acknowledges that “livestock carcass disposal in California is complex and highly regulated by several state agencies. With very few options available to the producer…” and was preparing Regional Carcass Disposal Emergency Response Action Plans. As of July 2025, such plans do not appear online.

At H5N1’s presumed California dairy peak, there were likely several thousand H5N1 infected dead cows in the Central Valley and several guidelines for farmers to consider, but very little clarity on required action. According to CalEPA/CDFA 2006 guidelines, the best approach is to temporarily store infected carcasses until a rendering facility can collect them. However, enforcing proper “storage” appears to have fallen short, increasing opportunities for disease spillover into waterways, wild animals, and humans as the carcasses sit for pickup.¹⁶ Overall, updated livestock carcass management guidance that includes low cost¹⁷ required components responsive to high death-rate emergencies is needed.¹⁸

Require biosecurity plans submission to the California Department of Public Health or another relevant agency.

Biosecurity Plans are a comprehensive set of practices designed to prevent the introduction and spread of a virus within and between livestock and farmworkers. Specific on-farm Biosecurity Plans are commonly cited as a key defense to animal disease outbreaks. However, simply having a plan is insufficient; effective implementation is crucial.

Generally, California dairies are not required to have biosecurity plans. However, they are encouraged when participating in the California Secure Food Supply program (SFS) and when obtaining movement permits. And, during animal disease outbreaks, those participating in the SFS must have a biosecurity plan. Notably, biosecurity plans are produced, managed, stored, and supervised internally by a “biosecurity manager.” Only during an animal disease outbreak may CDFA request SFS participating dairies to submit their plans for review or conduct dairy site visits. Ultimately, this largely optional process poses several challenges. Among others, it makes preemptive risk management difficult, obfuscates a plan’s contents, prevents farmworkers or community members from knowing whether a farm is violating their plan, and makes confirming a plan meets SFS’s requirements difficult.¹⁹

Furthermore, while auditing is allowed at SFS participating dairies during a disease emergency, it is unclear whether agencies have the capacity to thoroughly audit. Indeed, only Fresno, Sonoma, Tulare, Kings, Imperial, San Joaquin and Stanislaus counties have local dairy inspectors. And, with a 23 percent vacancy rate (much of which is concentrated in its enforcement division) in 2024, Cal/OSHA may be unable to thoroughly conduct inspections itself.²⁰

Requiring dairy biosecurity plan submission to CDFA, or another relevant agency, would significantly increase transparency with little agency resources. Submission to CDFA or another government agency is a low-time and cost commitment for agencies (they need only store the plans) and SFS participating dairies (who already have plans). Given limited agency capacity to review and enforce plans, agency submission would make them publicly accessible, thus enhancing community oversight, information sharing, and accountability.

Conclusion

According to a 2023 Harvard study, “more zoonotic diseases originated in the United States than in any other country during the second half of the 20th century.” From the largest recorded numbers of swine-origin influenza in the world since 2011, to the dramatic rise in avian flu at the end of 2024, our current animal agriculture system perpetuates disease spread and the many animal welfare and human health implications that follow. While non-exhaustive, the spring policy practicum report systematically outlines many of the structural gaps that have helped lead to this phenomena. With a series of pragmatic, high-impact, localized recommendations, this report identifies several ways of reducing zoonosis in California’s Central Valley and beyond.

1. “New USDA Data Shows California Mega-Dairy Herds Grew an Average of 72% In 20 Years,” Food & Water Watch, 21, Feb. 2024, https://www.foodandwaterwatch.org/2024/02/21/new-usda-data-shows-california-mega-dairy-herds-grew-an-average-of-72-in-20-years/ (indeed, California has the most dairy cows on factory farms in the Nation, over double what the next highest state, Wisconsin, has).

2. Ly, Hinh. “Highly pathogenic avian influenza H5N1 virus infections of dairy cattle and livestock handlers in the United States of America.” Virulence, vol. 15, no. 1, 17 April 2024, doi: 10.1080/21505594.2024.2343931.

3. Early estimates indicate that at its Central Valley peak, on average 15-20% of a cows in infected herds tested positive for H5N1, see Rust, Susanne. “Bird Flu Deaths Increasing among California Dairy Cows.” Los Angeles Times, 4 Oct. 2024.

4. See, e.g., Mike Davis, The Monster at Our Door: The Global Threat of Avian Flu, The New Press, 2005; Marie, Veronna, and Michelle L Gordon. “The (Re-)Emergence and Spread of Viral Zoonotic Disease: A Perfect Storm of Human Ingenuity and Stupidity.” Viruses vol. 15, no. 8 ,1638, 27 Jul. 2023, doi:10.3390/v15081638.

5. The practicum was led by the Climate and Energy Policy and Environmental and Natural Resources Law & Policy Programs at Stanford Law School.

6. Crystal Heath, Veterinarian and Our Honor Co-Founder, interview May 5, 2025; validated by interview with Dr. Elizabeth Noth, Senior Industrial Hygienist, Cal/OSHA, May 14, 2025.

7. Dr. Elizabeth Noth, Senior Industrial Hygienist, Cal/OSHA, interview 14 May 2025.

8. Crystal Heath, Veterinarian and Our Honor Co-Founder, interview May 5, 2025; validated by interview with Dr. Elizabeth Noth, Senior Industrial Hygienist, Cal/OSHA, May 14, 2025.

9. APPENDIX 5 of the report.

10. Rust, Susanne. “California Dairy Farmers Get $230 Million to Help Cover Costs of Bird Flu Losses.” Los Angeles Times, 28 July, 2025; (quoting findings from public records requested by Farm Forward); Bird Flu Deaths Increasing among California Dairy Cows.” Los Angeles Times, 4 Oct. 2024; “Highly Pathogenic Avian Influenza (HPAI) H5N1 Virus in Livestock.” CDFA: AHFSS, 21 May 2025 (as of May 21, 2025, at least 766 California dairies have had H5N1 cases.).

11. At a 15% mortality rate across 766 dairies with, at minimum, 500 head, roughly 57,450 dead cows have needed managing during the recent H5N1 outbreak. See, Smith, Aaron. “Where Are California’s Dairy Cows?” The Dairy News, 20 Feb. 2024 (explaining that over 90% of California dairy cows are on farms with over 500 head).

12. See APPENDIX 3 Key Waste Management Guidance Documents of the report; Douglas, Leah. “Cows Dead from Bird Flu Rot in California as Heat Bakes Dairy Farms.” Reuters, 17 Oct. 2024 (generally, it appears that leaving animals for pickup by a rendering facility is the preferred method, but the dramatic increase of dead cattle and high temperatures caused a delay); “Home.” Agricultural Commissioner/Sealer, 2022, agcomm.co.tulare.ca.us/ (lacking information regarding dead animal management).

13. See APPENDIX 3 Key Waste Management Guidance Documents of the report.

14. 9 C.F.R. 56.2 “Cooperation with States”; 9 C.F.R 56.10(a)(8) regarding required and APHIS approved disposal plans for poultry owners for indemnity eligibility; “Carcass Management during Avian Influenza Outbreaks.” US EPA, 30 Oct. 2017, www.epa.gov/disaster-debris/carcass-management-during-avian-influenza-outbreaks.

15. See APPENDIX 3: Key Waste Management Guidance Documents of the report.

16. Klein, Kerry. “Photos of Dead Cattle Show Bird Flu Is Overwhelming Tulare County. How Did the Virus Get In?” KVPR | Valley Public Radio, 11 Oct. 2024, www.kvpr.org/health/2024-10-11/photos-of-dead-cattle-show-bird-flu-is-overwhelming-tulare-county-how-did-the-virus-get-in; Johnson, Don. Emergency Animal Disease Regulatory Guidance for Disposal and Decontamination. CalEPA, 2 Dec. 2004, pp. 7–8, calepa.ca.gov/wp-content/uploads/2016/10/Disaster-Documents-EADisease.pdf (explaining that there are few rendering plants in California and that carcasses must be secured and separated while waiting for pickup and during transit).

17. “Emergency Animal Mortality Preparedness Rendering Service Disruption in the Central Valley Mortality Disposal Options for Dairy.” CDFA, 2 Sept. 2022, p. 5, https://www.cdfa.ca.gov/AHFSS/pdfs/dairy_emergency_mortality_disposal_preparedness_guidance_final_09012022_cdfa.pdf (indicating that, in state of emergency where select landfill dumping is permitted, using the Visalia landfill for Tulare County would likely cost a farmer several hundred dollars).

18. While AB 411 (Livestock carcasses: disposal: composting) awaits the Governor’s signature, critics worry creating a composting exception for animal agricultural operations to dispose of dead animals on-site will only allow disease spread to grow.

19. Notably, a farm may elect to submit their plan prior to an outbreak and have it SFS approved, this allows them to resume activities more quickly during an outbreak. However, there doesn’t appear to be any regular plan review, biosecurity-implementation review, or other non-emergency audit authority.

20. Cal/OSHA website reports a 10% vacancy rate for June 2025, warranting further research into the vacancy numbers as compared to needed enforcement staff. As of publication, there is no 2025 external audit or review.