CARB At-Berth Regulations: What Vessel Operators and Ports Need to Know

Last updated on March 10, 2026

A complete guide to California’s at-berth emissions rules, compliance timelines, approved solutions, and how to prepare for expanding requirements through 2027.

California’s at-berth emissions rule is one of the most stringent port air-quality regulations in the world. Administered by the California Air Resources Board (CARB), the rule requires ocean-going vessels to significantly reduce emissions like particulate matter (PM) and nitrogen oxides (NOx) while docked at California ports.

To comply, vessels must use one of only two CARB-approved solutions: shore power (plugging into the electrical grid and shutting down auxiliary engines) or a CARB-Approved Emissions Control Strategy (CAECS), such as emissions capture and control technology, like STAX. As the regulation expands through 2027 to cover additional vessel types (including roll-on/roll-off vessels and tankers), ports and fleet operators must plan for stricter compliance deadlines.

Understanding how the rule works—and how approved solutions differ operationally and economically—is critical for meeting deadlines, avoiding penalties, and preparing for future regulatory expansion.

What is the CARB at-berth regulation?

The CARB at-berth regulation is a California air-quality rule that requires ocean-going vessels to reduce harmful emissions while docked at California ports.

When ships are at berth, they typically run on auxiliary diesel engines to power onboard systems. These engines emit toxic pollutants such as PM, NOx, and sulfur oxides (SOx), which can lead to health issues for those in surrounding communities, including respiratory problems, cardiovascular diseases, and forms of cancer. They also contribute to environmental degradation and long-term climate impacts.

California’s major ports are among the busiest in the world — the Ports of Los Angeles and Long Beach alone are responsible for producing roughly 100 tons of smog daily, comparable to emissions from 6 million vehicles. California enacted the at-berth rule to reduce pollution and protect public health.

When do CARB at-berth regulations take effect?

CARB first introduced at-berth emissions reduction regulations in 2007. The original requirements took effect in 2014 and by 2020, dramatically reduced harmful emissions by 80%.

In 2023, updated regulations began phasing in expanded requirements and additional vessel categories. These updates continue through 2027.

Once fully implemented, the revised rule is expected to achieve:

• 90% reduction in pollution from covered vessels
• 55% reduction in potential cancer risk for communities near major ports, including Los Angeles, Long Beach, and Richmond

Compliance timeline by vessel type

What are the penalties for non-compliance with CARB at-berth regulations?

Failure to comply with CARB’s at-berth regulation can result in significant financial penalties.

Under Section 43016 of the California Health and Safety Code, CARB may impose fines of up to $37,500 per violation. Maximum penalty amounts increase annually based on the California Consumer Price Index (CPI).

Penalties may apply to:

• Vessel operators
• Terminal operators
• Port authorities
• Third-party CAECS providers

CARB evaluates violations on a case-by-case basis, and enforcement actions are detailed annually in the CARB Enforcement Division’s Annual Report.

Which California ports are subject to CARB at-berth regulations?

CARB’s at-berth rule applies to regulated marine terminals in California that receive 20 or more visits from a regulated vessel category in any calendar year. This includes:

• The Port of Los Angeles
• The Port of Long Beach
• The Port of Oakland
• The Port of San Francisco
• The Port of San Diego
• The Port of Benicia
• The Port of Richmond
• The Port of Carquinez Strait
• The Port of Crockett
• The Port of Hueneme

Any terminal that receives fewer than 20 vessel visits in a year is defined as “low activity” or “low-use” and is not subject to emissions control requirements.

The regulation applies to multiple stakeholders across port operations:

• Vessel operators: Must ensure their ships meet emission standards when at berth.
• Terminal operators: Required to provide the necessary infrastructure to support compliance efforts.
• Ports: Must facilitate the implementation of CARB regulations and monitor compliance.

What emissions solutions qualify under CARB rules?

There are two primary emissions solutions that qualify under CARB at-berth regulations:

1. Shore power
2. A CARB-approved capture and control system, like STAX

Ports are required to leverage these solutions to help all vessel types comply and may work with third-party-operated CAECS. Incentive funding is available for these programs.

Shore power

Shore power, also known as cold ironing, allows vessels to shut down their auxiliary engines and connect to the local electrical grid while at berth.

This approach:

• Reduces local emissions
• Requires significant landside electrical infrastructure
• Requires vessel retrofits (which is not possible on all vessel types)
• Depends on grid capacity

Estimates place the cost of retrofitting a ship to plug into shore-side power between $500,000 and $1.5 million per vessel. And while many California ports have begun making upgrades to accommodate shore power, creating enough infrastructure to service all vessels will take time.

Emissions capture and control

Emissions capture and control systems treat exhaust without requiring vessel modifications.

STAX operates the only CARB-authorized emissions capture and control system that can serve all vessel types under the ruling (container, autocarriers, and tankers), and serves as a solution for many vessels that cannot use shore power.

STAX’s emissions capture and control technology:

• Attaches directly to a vessel’s exhaust system while docked
• Requires no retrofits
• Removes up to 99% of PM and 95% of NOx.
• Captures boiler emissions not addressed by shore power
• Allows operators flexible booking when their ship is at berth

The STAX Advantage

Meeting CARB’s expanding at-berth requirements will require coordination between vessel operators, terminals, and ports.

With no need to complete expensive retrofitting, STAX’s emissions capture and control system serves as a smart and cost-effective bridge solution that helps ports and vessels achieve compliance today while long-term electrification efforts continue.

As the 2021 California Air Resource Board’s grant recipient for technology advancement, and the largest CARB-authorized fleet capacity for at-berth emissions control, STAX supports ports and vessel operators in preparing for emissions regulations of the future.

STAX is currently operating at:

• The Port of Long Beach
• The Port of Los Angeles
• The Port of Oakland
• The Port of Hueneme
• The Port of Benicia

Learn more about the regulatory landscape for maritime emissions and get in touch with our team to help your fleet achieve compliance efficiently and effectively.