Cumulative effects & climate change

Cumulative effects are the aggregate result of incremental direct and indirect effects of a project or plan, effects of past and present actions, and effects of other reasonably foreseeable future actions on a resource of concern. Cumulative effects generally relate to concerns over future climate threats, changes in land use, trends in habitat quality, environmental and public health, and more.

Use this information to prepare cumulative impacts analyses for projects requiring an Environmental Assessment (EA) or an Environmental Impact Statement (EIS).

WSDOT recommends that a project’s indirect effects be considered and addressed alongside direct impacts in the environmental document. See Environmental Manual Chapter 412 for more information. Information on completing project level greenhouse gas evaluations is available on our Air quality, greenhouse gas and energy webpage.

Public scoping comments

For NEPA EA’s and EIS’s, the project team should examine comments submitted during public scoping. Any effects that do not tie directly to project impacts but may impact resources that are also affected by the project, should be addressed in the cumulative effects section. Keep in mind, effects that tie directly to the proposed project are evaluated as direct impacts.

Identify prior studies that can inform your project-level analysis

Determine if a planning level study was completed for the project area. This may be a locally developed plan or a WSDOT corridor study. Environmental Manual Chapter 200 Environmental considerations in transportation planning (PDF 274KB) explains how planning projects (any pre-NEPA plan) can consider environmental issues. If WSDOT conducted a planning effort, look to see if that study examined land use trends, or if it contains a summary of climate change vulnerability identified for the corridor. Guidance for considering effects of climate change in WSDOT plans (PDF 606KB) – this document provides direction on considering climate change impacts during the transportation planning process.

Identify any local or regional transportation plans, Growth Management Act comprehensive plans, climate change resilience plans, and natural hazard mitigation plans that relate to the project area.

Slow down – lives are on the line.

In 2022, speeding continued to be a top reason for work zone crashes.

Even one life lost is too many.

Each year about 670 people are killed nationally in highway work zones. In 2022, Washington had six fatal work zone crashes on state roads.

It's in EVERYONE’S best interest.

95% of people hurt in work zones are drivers, their passengers or passing pedestrians, not just our road crews.