Posted by Western United Dairies | October 2025
When Governor Gavin Newsom signed Assembly Bill 411 (AB 411) into law earlier this month, California’s dairy farmers reached a long-awaited milestone. For years, producers have sought more practical, affordable, and environmentally responsible options for managing animal mortalities. The new law—known as the Caring About the Terrain, Livestock, and Ecosystems (C.A.T.T.L.E.) Act—finally makes that possible by authorizing on-farm composting of livestock mortalities under approved conditions.
Why This Matters
Until now, California regulations prohibited composting livestock mortalities, leaving producers with very few disposal options. With only a handful of rendering facilities still operating statewide—many far from North Coast and Northern California dairies—rendering has become increasingly expensive and logistically challenging. AB 411 provides a much-needed, proven alternative that has been safely implemented in more than 40 other states.
The bill, championed by Western United Dairies and a coalition of agricultural and environmental partners, passed the Legislature without a single “no” vote—an uncommon achievement that underscores its broad support and practical benefits. Importantly, AB 411 applies statewide to all livestock operations, regardless of size or location—ensuring that every dairy, from small family farms to large multi-site operations, can benefit from this new law.
When Does the Law Take Effect
AB 411 officially takes effect January 1, 2026, but that doesn’t mean composting can start right away. Before any on-farm composting can occur, the California Department of Food and Agriculture (CDFA) must develop and adopt Best Management Practices (BMPs) for livestock composting. These BMPs will define how composting can be done safely—protecting water quality, controlling odors and wildlife, and ensuring biosecurity.
Until those BMPs are finalized and approved by CDFA Secretary Karen Ross, composting animal mortalities remains prohibited under state law.
What to Expect from the BMP Process
Once the law takes effect, CDFA will lead an interagency process to develop the composting standards. The department will consult with several “sister agencies,” including:
- CalRecycle,
- The California Department of Public Health,
- Regional Water Quality Control Boards, and
- Local enforcement agencies.
Researchers and industry experts will also provide technical input to ensure the rules are workable for dairy operations of all sizes.
The BMPs will likely include requirements for:
- Preventing leachate and runoff that could contaminate water.
- Managing odors, flies, and scavengers.
- Tracking time and temperature in compost piles to ensure safe decomposition.
- Keeping compost on-site—only using material and finished compost from the same dairy.
What Producers Should (and Shouldn’t) Do Right Now
For now, nothing changes with your mortality management program.
- Do not cancel rendering contracts. The Regional Water Boards still require documentation that carcass disposal complies with your Dairy General Order.
- Stay informed. AB 411 creates a new option, but implementation will take time and careful coordination.
How WUD and Industry Partners Are Helping
Western United Dairies, the California Dairy Quality Assurance Program (CDQAP), and the California Dairy Research Foundation (CDRF) are working closely with CDFA and other agencies to ensure producers have the information and tools they need once composting becomes available.
These groups will help roll out:
- Producer-friendly training and guidance materials.
- Compliance checklists for integrating composting into your dairy management plan.
- Updates on regulatory progress and BMP development.
Looking Ahead
AB 411 represents a major step forward for California’s dairy community—balancing environmental protection, animal health, and operational flexibility. The law’s statewide applicability ensures that dairies of every size, in every region, can benefit once the BMPs are in place. With thoughtful implementation and strong producer engagement, on-farm composting can become another valuable tool in California dairy farmers’ toolbox.
WUD will continue to provide updates through this blog, our newsletter, and podcast as CDFA’s process unfolds.
Sponsored By
