Reasonably foreseeable effects
Any effects planned for analysis under NEPA and SEPA should be reasonably foreseeable.
SEPA cumulative impacts
To satisfy SEPA requirements on Environmental Impacts Statements (EISs) level projects, the project team should examine comments submitted during public scoping. Any impacts 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 impacts section of the SEPA documentation. Keep in mind, impacts that tie directly to the proposed project are evaluated as direct impacts, and all impacts must be reasonably foreseeable.
Identify prior studies that can inform your project-level analysis
Determine if a planning level study was completed for the project area. For example, this may be a locally developed plan or a WSDOT corridor study. Environmental Manual Chapter 200: Environmental considerations in transportation planning (PDF 427KB) explains how planning studies (any pre-NEPA/SEPA plan/study) should consider environmental issues.
Identify any local or regional transportation plans, Growth Management Act comprehensive plans, and natural hazard mitigation plans that relate to the project area.
If WSDOT conducted a planning effort, determine how information might be used to inform preliminary NEPA/SEPA scoping efforts.
Analyze reasonably foreseeable effects
NEPA reasonably foreseeable effects analysis
Under NEPA, environmental analyses should evaluate reasonably foreseeable effects associated with the proposed action and alternatives. The analysis should focus on effects that have a reasonably close causal relationship to the proposed action and are relevant to decision-making.
Reasonably foreseeable effects analysis should match the project scope and affected resources. Analysts should use available planning information, technical studies, agency coordination, and professional judgment to determine the appropriate level of analysis for each affected resource.
Where future actions or future environmental conditions are discussed, the analysis should explain the relationship between the proposed project and the reasonably foreseeable effects being disclosed.
SEPA reasonably foreseeable and cumulative impacts analysis process
All impacts analyzed under SEPA should be reasonably foreseeable. SEPA EISs should also evaluate cumulative impacts.
EIS-level SEPA documentation should include cumulative impacts analysis. The analysis should focus on resources affected by the proposed action and evaluate whether the project’s impacts, when considered with other relevant past, present, and reasonably foreseeable future actions, may contribute to cumulative impacts.
The scope and methodology of the analysis should be consistent with the project scale, affected environment, and significance of potential impacts. Analysis should be limited to resources affected by the proposed action. If the project does not affect a resource, then it cannot contribute to a cumulative impact on that resource. The one exception to this is climate change (refer to the climate change-related effects webpage for more information).
To avoid confusion when designing your analysis, we advise the consistent use of the phrase: “the project’s contribution to cumulative impacts on [resource].”
Analysts should evaluate whether the project’s impacts, when considered with relevant past, present, and reasonably foreseeable future actions, may collectively contribute to a cumulative impact.
The SEPA documentation lead determines how the analysis will be documented. Options include:
- Prepare a separate cumulative impacts section.
- Integrate the disclosure of cumulative impacts within the affected resource sections.
Discipline report finalization should continue to be coordinated through the project team and appropriate subject matter experts. Please see the Contacts tab for information
