California – San Diego Zoning for Community Composting

San Diego County updated its zoning code with Zoning Ordinance Section 6977, Organic Materials Processing in 2022 to specifically support community composting activities. These updates were made partially in support of San Diego County’s goal to achieve net zero carbon emissions by 2035.

Previous regulations allowed farmers and residents to compost their own materials without a permit, but lacked options for composting of materials from off site (e.g. neighbors or nearby farmers). Previously, any composting operation processing off-site materials required a major or minor use permit, which could cost $15,000-$100,000 and take 1-2 years to process, posing an almost impassable hurdle to on-farm and community-based composting sites that might want to compost off-site materials. These limitations meant that organic materials were, by default, sent to a large, centralized composting facility or a landfill. 


New Zoning Ordinance Supports Community Composting

The new ordinance promotes community composting by removing large facilities as the sole option and making organics processing more accessible to local compost sites on farms, in backyards, and at community gardens (the graphics below illustrate this shift). Permit requirements were reduced to allow for more small and medium-sized composting operations and compost training is offered through a partnership between the Department of Public Works and the Solana Center to ensure best management practices on site.

ILSR’s October 2022 webinar, Government Support for Community Composting Part 4: A Menu of Options – Zoning, Grants, and Contracts, featured a presentation on this zoning update by Tyler Farmer of the San Diego County Sustainability Planning Division.


The updated ordinance impacts farms, community gardens, residential composters, and commercial operations. Depending on the type of operation, different limitations apply for organic material sourcing and processing as well as quantity of materials allowed at a site (see drop-downs below for more detail on each type of site). Based on the applicable land use regulations on site, rules differ for distribution and sales of finished compost.

The ordinance also added a definition of Community Composting:

Community Composting: Refers to the scale and geographic focus of the composting activities. This type of composting is small in scale (20 cubic yard maximum) and is meant to facilitate composting on the neighborhood level. Community composting is not commercial and can occur within residential and agricultural settings.”


All composting operations are subject to operational, siting, and permitting requirements:

  • A Best Management Practices Plan (BMP Plan) is required for all operations that describes the details of organic materials processing on site and demonstrates compliance with operational and sitting regulations. 
  • An Odor Impact Minimization Plan (OIMP) must be submitted to the County Planning & Development Services, if required by the California Code of Regulations (CCR) for composting and in-vessel digestion operations. 
  • Organic composting sites may be inspected by the County for a variety of reasons.   


Zoning Verification Permit

Community gardens and residential composting operations do not require permits as long as organics volumes are below 100 cubic yards or 20 cubic yards, respectively. A new Zoning Verification Permit was developed for commercial operations handling 100 cubic yards or less and on-farm composters accepting organic materials from off site. The new permit structure increases opportunities for farms and small-to-medium commercial composting operations to work with community composters by reducing the costs and time required for permit approval. See Table 1 for more details on site permit requirements.


Composting is allowed as an accessory activity on any active farm and a maximum of 1,000 cubic yards of finished compost may be donated annually. Organic materials sourced on site may be processed in unlimited volumes and do not require a permit (see Table 1 for details).

Sites subject to specific land use regulations (A70, A72, C37, C38, C40, S88, S90, S92, M50, M52, M54, M56, and M58) may accept organic materials from any source and finished compost may be sold or donated in any amount. Chipping and grinding (e.g. mulch processing) may also occur on farms, but it must not be the primary method of organic materials processing. Finished compost from an on-farm site is considered an agricultural product. 

Organic materials sourced off site are subject to volume limitations and permit requirements as described in Table 1. Finished compost products and organic materials may be shared between composting sites if they are under the same ownership or leased by the same owner. Providers of organic materials are also allowed to share finished compost products. Independent farms may form groups and sharing of materials and products may be allowed. 

Composting is allowed (as an accessory activity) on site at community gardens and off-site organic materials from any source may be accepted for processing. Sales of compost are not allowed, but finished compost may be donated in any amount. No permits are required as long as the total volume of organic material on site at one time does not exceed 100 cubic yards or 750 square feet (see Table 1 for a summary). Similar to farm operations, chipping and grinding may occur on site, but cannot be the primary organic materials processing method. 

Sites designated as residential through use regulations RS, RD, RM, RV, RU, RMH, RR, RRO, and RC may process organic materials on site and no permits are required as long as the total volume of organic material on site is less than 20 cubic yards (see Table 1 for a summary). Neighbors may share organic materials and finished compost. 

Organic materials are limited to vegetative food material and green material only, but if the site is a farm, agricultural materials may also be accepted. Processing of materials must occur within an enclosed container and finished compost may be donated in any amount, but sales are prohibited.

Organic material processing may be a primary commercial activity for specific use regulations (A70, A72, C37, C38, C40, M50, M52, M54, M56, M58, S80, S82, S86, S88, S90, S92, and S94). For these sites, the total volume of organic material on site is limited to 100 cubic yards or 750 square feet at any given time (see Table 1 for a summary). If volumes exceed 100 cubic yards or 15 tons per day, standards and requirements for large commercial operations apply (Ordinance Section 6902). Materials may be processed in an enclosed container, including anaerobic digestion systems.

Off-site organic materials may be accepted from any source for processing and finished compost products may be sold or donated in any amount (unless limited by administrative or use permits). Similar to farms, chipping and grinding is allowed on site as an accessory activity to support operations. 

“Management of Organic Materials Processing shall align with the current General Waste Discharge Requirements for Commercial Composting Operations of the State Water Resources Control Board.” 


Table 1: Compost Site Operational Limitations and Permit Requirements (Click to Expand)


Operational and Siting Requirements

All Organic Materials Processing sites must comply with operational and siting requirements in addition to the permits and volume limitations described above. Sites are also subject to volume and material limitations in California Code of Regulations for composting operations (see Table 1 for greater detail). San Diego County’s Fire Code limits piles to 12 feet in height, 100 feet in width and 200 feet in length. 

Sites are required to minimize wastewater generation. Wastewater from both stormwater runoff and leachate must be managed in compliance with all federal, state, and local permits. Wastewater runoff during weather events must also be minimized through proper coverage of materials or equivalent management practices.

Site operators are required to prepare, implement, and maintain operations to ensure treatment and control that meets pathogen reduction requirements specified by CalRecycle. Additionally, all organic materials processing operations must minimize impact to surrounding areas through best management practices.


More Information

Original post from May 23, 2023

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Follow Megan Matthews:
Megan Matthews

Megan Matthews was a research fellow with ILSR’s Composting for Community initiative assisting with research, data analysis, and administrative support. She is interested in using data and outreach to promote sustainability, food equity, and environmental justice through the lens of agroecology.

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Follow Sophia Jones:
Sophia Jones

Sophia Jones is the Policy Lead with ILSR’s Composting for Community initiative, where she researches, analyzes and supports the building of US policy that advances local composting. Her background in sustainable development and agriculture reflects her interest in solutions-based, community-led development initiatives.