Washington State DOT (WSDOT) Guidance for Project-Level Climate Change Evaluation

The Washington State DOT (WSDOT) issued this guidance to assist the agency’s project planners in considering climate change impacts, which is required for all WSDOT projects subject to the National Environmental Policy Act (NEPA) and Washington’s State Environmental Policy Act (SEPA). In addition to obligations under NEPA and SEPA, WSDOT’s 2011-2017 Strategic Plan directs the agency to evaluate future climate-related risks and identify strategies to reduce risk. The guidance provides a standard process for analysis and template language to enable planning-level consideration of Washington’s projected climate impacts.

WSDOT relies on climate information from the Washington Climate Change Impacts Assessment conducted by the University of Washington in 2009 and updated in 2013.  Additionally, WSDOT conducted a statewide Climate Impacts Vulnerability Assessment of all of the agency’s infrastructure, which will help project planners consider the vulnerability of future projects to climate change impacts. The guidance indicates that WSDOT project teams are expected to use the results of the vulnerability assessment and other available climate projections,  alongside their own knowledge of existing conditions, to satisfy WSDOT’s directive.

The guidance also encourages WSDOT’s NEPA specialists to expand how they describe the “affected environment” based on climate science. Following the White House Council on Environmental Quality (CEQ) 2010 Draft NEPA Guidance on Consideration of the Effects of Climate Change and Greenhouse Gas Emissions, WSDOT directs project teams to consider future impacts of climate change on projects “designed for long-term utility” by utilizing scientifically-based projections in their analysis rather than relying on past trends.

Project planning teams are directed to ask and answer: “how will my project be affected by climate change?” The guidance provides the following steps to guide the process:

  1. Utilize the results of WSDOT’s Climate Impacts Vulnerability Assessment to assess vulnerabilities to existing WSDOT facilities in the project area.
  2. Contact the WSDOT Environmental Services Policy Branch Manager for assistance in determining the climate change threats specific to the project area. Determine whether there is regional or site-specific climate data that can be utilized.
  3. Direct the project’s technical specialists to apply the information gathered in Steps 1 and 2 in their NEPA and SEPA analyses and other impact mitigation proposals.
  4. Document findings about projected climate threats in the cumulative effects section of the analyses, or other specific discipline sections where appropriate, including whether climate change will exacerbate effects on (a) environmental resources, and (b) vulnerable populations.
  5. Document the ways the project will be designed to be resilient to anticipated climate threats, and consideration of ways to address vulnerability of environmental justice populations.

The guidance provides template language for use in the cumulative effects section of a NEPA or SEPA Environmental Assessment or Environmental Impact Statement, as well as a list of definitions and terminology to standardize the language used in WSDOT project documentation. Finally, it highlights two examples of how project-level environmental review considered climate change impacts: State Route 522 at the Snohomish River Bridge, which deepened bridge footings to protect against changes in peak flow that could increase bridge scour, and the Mukilteo Multimodal Terminal, which considered sea-level rise projections in evaluating and selecting a preferred siting alternative.

WSDOT first developed guidance on addressing both greenhouse gas emissions and climate change impacts in 2009, making it the first DOT in the country to incorporate these considerations consistently in environmental review. Since 2009, WSDOT has revised the guidance several times, including by separating it into two guidance documents: one to consider project-level greenhouse gas emissions, and one to consider project-level climate change evaluations (the focus of this case study). The most recent revision was in January 2017, and includes guidelines to evaluate whether climate change will exacerbate the impacts of a proposed project on environmental resources and vulnerable populations.


This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on July 30, 2018.


Publication Date: January 2017 Update

Related Organizations:

  • Washington State Department of Transportation


Resource Category:

Resource Types:

  • Agency guidance/policy

States Affected:

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