Statutory authority to regulate composting is found in the Public Resources Code. Composting activities were not regulated by the California Integrated Waste Management Board (now CalRecycle) prior to July 15, 1993, when the first version of the composting regulations took effect. These regulations only applied to the composting of green material and had a more prescriptive nature (specifying the method to achieve conditions of compliance) than the current regulations. Subsequently, comprehensive composting regulations were developed which included additional feedstocks and removed prescriptive requirements. The language in the next version and in current regulations attempts to define the conditions for compliance without specifying a particular method to protect the environment and/or public health and safety. These regulations, the second version, took effect on July 31, 1995 and applied to traditional high temperature composting operations which intentionally composted organic materials. Activities that inadvertently composted materials were precluded from the requirements of these regulations. Several activities were explicitly excluded from these regulations, including vermicomposting and chipping and grinding. However, significant health, safety, and environmental impacts were identified from the operation of these activities.

As a result of these impacts, the Board adopted emergency regulations for chipping and grinding, and storage of organic materials at its February 26, 1997 meeting. In addition, clarification was given on which activities associated with vermicomposting were subject to Board regulations. The regulations were approved by the Office of Administrative Law and became effective on April 7, 1997. Permanent regulations, the third version, took effect on January 8, 1998. These regulations did not place storage and chipping and grinding activities into permitting tiers. However, staff was directed by the Board to accomplish this at a later date. The Sustainability and Waste Compliance & Mitigation Programs jointly developed the fourth and current version of the composting regulations, which were adopted on April 4, 2003 and the guidance for implementation of these regulations.

As part of Strategic Directive 8, stakeholder feedback was solicited on 14 compostable material handling issues and potential approaches for addressing these issues from 2011-2014. The revision of existing Title 14 and Title 27 regulations addresses compostable materials, transfer/processing, permit application form, and permit exemptions. The Director initiated formal rulemaking for the “Proposed Compostable Materials Handling and In-Vessel Digestion Regulations” in October 2013. CalRecycle initiated the formal rulemaking process on October 10, 2014, and the 45 day written comment period closed on December 5, 2014.



LEA Authority Over Odors from Compostable Materials Handling:

Historical Legislation:

Below is historical legislation extending the LEAs authority over odors emanating from composting operations and facilities:


The regulations adopted on April 4, 2003 accomplished major changes. Guidance on specific issues and situations is available in question/answer format to assist with the implementation of the compost regulations. If you are part of a local solid waste enforcement agency and have any questions that are not answered by the available Q&As, please contact your CalRecycle liaison. New issues will be answered by the CalRecycle implementation team and posted.

In April 2008 regulations allowing on-site composting of mammalian tissue when associated with research designed to obtain data on pathogen reduction became effective. The regulations also amend existing emergency waiver standards that authorize an enforcement agency to waive state minimum standards associated with a locally-approved temporary composting activity. These regulations will gather much needed data that will hopefully lead to more alternatives to disposal in the future.

The affected code sections for the major changes adopted in April 2003 are below.

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