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Environmental Sustainability

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Protecting the Environment

Transportation is responsible for 38% of the state’s greenhouse gases each year.1 Auto usage and congestion are growing throughout the Megaregion. Traffic entering San Francisco has grown by 27% since 2010.2 

Public transportation improvements are at the forefront of President Biden's agenda. The State of California is on the leading edge of a nationwide effort to upgrade and modernize the state’s transportation systems to reduce the greenhouse gas emissions caused by single-occupancy vehicles. 

We’re planning ahead so that all current and future Link21 projects support and comply with federal and state environmental requirements. 

Link21 will advance state and national climate goals and is one of the top-ranked transit projects for regional greenhouse gas reduction.

An improved train network will provide convenient alternatives to driving, improve air quality, and reduce climate-changing pollution caused by cars. An improved train network will also support equitable, livable communities that optimize land uses, and maximize access and mobility for all populations.

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Environmental Constraints and Opportunities

Read our Environmental Constraints and Opportunities (ECO) Report, Executive Summary, or check out the mapbooks in the Document Library to learn about the major environmental constraints and opportunities that are informing the development of the Link21 concepts. The ECO Report identifies key opportunities to meet the Program’s Goals and Objectives, and key constraints that will inform the development of concepts into alternatives.

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Link21 Environmental Analysis

Link21 is committed to a fully integrated planning and environmental process with public and stakeholder input. As required by federal and state laws, Link21 will perform a full detailed environmental analysis during later phases of the Program. However, the Link21 Team is planning ahead so that all current and future work supports and complies with the environmental process. United States Department of Transportation guidance regarding planning and environmental linkages (also known as PEL) is guiding the Program’s planning and public/stakeholder input to arrive at a project to be carried forward into more formal and detailed environmental compliance.

National Environmental Policy Act (NEPA)

NEPA requires federal agencies to consider and disclose the effects of their actions on the quality of the human and natural environment. Because federal funding is anticipated for Link21, the Program will prepare NEPA-compliant environmental documents (such as environmental impact statements) for proposed projects, which includes analyses of:

  • Environmental impacts and potential benefits of the proposed action
  • Potential mitigations for adverse impacts
  • Adverse impacts that cannot be avoided

Stakeholders, including public agencies, tribal nations, and the public, will be involved in the Link21 NEPA evaluation.  

California Environmental Quality Act (CEQA)

CEQA requires public agencies to regulate activities that may affect the quality of the environment so that major consideration is given to preventing damage to the environment.

CEQA applies to all governmental agencies at all levels in California, including local agencies, regional agencies, state agencies, boards, districts, and commissions. The San Francisco Bay Area Rapid Transit (BART) and Capitol Corridor Joint Powers Authority (Capitol Corridor) will be the lead agencies for the CEQA process, which may include an environmental impact report identifying potential project alternatives, adverse and beneficial impacts, and possible mitigations if required.


train passing by a lake