CA Cracks Down on Landfill Methane With 2027 Compliance Rules

The California Air Resources Board adopted amendments to its regulation on methane emissions from municipal solid waste landfills. The amendments take effect Jan. 1, 2027, and would push compliance toward faster detection and fixes.

The rulemaking exposed a delegation issue. Air districts often enforce the program through memoranda of understanding, or MOUs. The South Coast Air Quality Management District warned in a November 2025 letter that a compressed process gave districts little time to evaluate a sweeping rewrite of rules they help administer. It tied the concern to a four-business-day review window and urged CARB to address timing, definitions, and delegation mechanics.

Background

CARB adopted the landfill methane regulation as an early action measure under AB 32. It requires landfill gas collection and control systems, surface emissions monitoring, and reporting. CARB treats the program as more than a methane rule. Since landfill gas carries methane and co-pollutants, CARB frames landfill methane control as a climate measure with direct air-quality and public-health consequences.

CARB doesn’t implement the program alone. Air districts often carry the day-to-day burden through MOUs that allocate inspection, plan review, enforcement, and fee collection. That structure makes district capacity a compliance variable when CARB adds more frequent monitoring and shorter response timelines.

What CARB Adopted

The rulemaking record reflects a simple premise: Advanced monitoring can identify emission events routine surveys may miss, and prompt operator response can reduce the duration and magnitude of releases. Three changes drive the compliance impact.

First, CARB elevated advanced detection, including satellite-based plume detection that flags elevated methane concentrations over a landfill. CARB also emphasized other methods suited to active working areas and locations staff can’t safely access on foot. For operators, this makes remote detection an operational response trigger, not a public-facing metric.

Second, CARB tightened the “find and fix” loop. CARB described more frequent monitoring, faster resolution once a leak is detected, and stronger action for recurring problems. Facilities should expect repeat problem areas to draw greater scrutiny.

Third, CARB paired these requirements with expanded reporting and oversight and emphasized public availability of reported information and data sharing with other agencies. Transparency requirements often harden the compliance record and can shorten the path to escalation.

CARB also confirmed broad applicability. The amendments reach active, inactive, and closed landfills. Closure may reduce operational complexity, and it rarely ends monitoring, maintenance, and documentation obligations.

That breadth also explains the reaction from implementing agencies. When CARB expands obligations across the landfill lifecycle, districts inherit more plan review, more field oversight, and more enforcement workload, often under MOUs and fee structures built for an earlier version of the program.

South Coast Letter

South Coast AQMD’s letter reflects a process-based intervention from a delegated implementing agency facing a tight timeline on a comprehensive rewrite. South Coast stated that CARB contacted air districts on Oct. 31, 2025, to advise that the proposed amendments were open for comment, after a single public workshop held on Dec. 18, 2024. South Coast said the comment schedule left four business days for review, and comments were brief and incomplete.

The district warned of an implementation gap and stated that existing MOUs will cease to apply once CARB adopts the new regulation. It also argued CARB had not engaged districts on replacement MOUs. For operators, that concern translates into uncertainty about who will review plans, how districts will process approvals, and how enforcement authority will function during the transition.

South Coast also challenged the usability of the proposed text. It flagged unclear structure, obsolete definitions, undefined new terms, and inconsistent use of defined terms. Ambiguity invites inconsistent interpretation and increases the likelihood that routine disputes turn into formal enforcement matters.

Additionally, South Coast highlighted timeline risk. It objected to deadlines that require CARB or delegated districts to approve or disapprove permits and plans on schedules the district said it can’t meet with current resources. The district also argued that certain installation timelines appear arbitrary and urged CARB to align with, or defer to, district permitting processes for construction requirements.

Implications

The Jan. 1, 2027, effective date offers time, but it demands early execution that must take place this year, including:

• Selecting monitoring methods; engaging vendors and contractors
• Updating monitoring and response procedures
• Revising recordkeeping and reporting systems
• Coordinating early with the implementing air district

Operators should treat remote plume detection as an incident-response trigger. Remote detection rarely identifies the precise component failure or operational cause. Regulators will expect the operator to bridge that gap through field verification, corrective action, and confirmation monitoring. A written response protocol that ties these steps to consistent documentation will reduce enforcement risk when a plume notice arrives.

Operators should also plan for district-facing process risk. South Coast’s letter signals that districts expect plan and permit review workloads that may exceed current capacity. Operators can reduce friction by engaging early, clarifying submittal expectations, and delivering complete applications that minimize iterative review.

Finally, operators should assume greater public visibility. CARB’s emphasis on public availability of reported information and interagency data sharing increases the likelihood that emissions and compliance records draw scrutiny beyond the permitting file.

What’s Next

CARB staff expect to circulate additional amendments in a 15-day comment package to address issues raised by industry, local governments, and air districts. That process would be followed by executive officer adoption of the additions.

The stated targets track the implementation constraints South Coast flagged. They include aligning timelines throughout the regulation, recognizing unique facility characteristics, adding flexibility for circumstances outside an operator’s control such as public safety power shutoffs, and making clarifications intended to support smoother implementation with regulatory partners.

For regulated businesses, the package will likely determine whether 2026 becomes an orderly compliance build or a year of permitting bottlenecks and interpretive disputes. Companies that own or operate California landfills should watch the 15-day text closely and submit targeted comments tied to operational realities.

This article does not necessarily reflect the opinion of Bloomberg Industry Group, Inc., the publisher of Bloomberg Law, Bloomberg Tax, and Bloomberg Government, or its owners.

Author Information

Thierry Montoya is a member of Frost Brown Todd’s environmental practice group, representing public and private sector clients in complex environmental, land use, and natural resources matters.

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