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SEPA/NEPA

What is SEPA?

The Washington State Environmental Policy Act (SEPA) provides a way to identify possible environmental impacts that may result from governmental decisions. These decisions may be related to issuing permits for private projects, constructing public facilities, or adopting regulations, policies or plans. Information provided during the SEPA review process helps agency decision-makers, applicants, and the public understand how a proposal will affect the environment. This information can be used to change a proposal to reduce likely impacts. For more information about the SEPA process, visit the Washington State Department of Ecology.

What is NEPA?

The National Environmental Policy Act (NEPA) was enacted by Congress in December of 1969, and signed into law by President Nixon on January 1, 1970. Federal agencies must comply with the NEPA process, which examines the environmental impact of projects resulting from government decisions. The Port of Seattle works with Federal Aviation Administration and Environmental Protection Agency surrounding NEPA decisions. For more information on the NEPA process, visit the Council of Environmental Quality.

Documents

Title Category
2025-02 Comprehensive Routine Maintenance and Repair Program Environmental Checklist Maritime
2025-02 Comprehensive Routine Maintenance and Repair Program Draft Determination of Non-Significance Maritime
2025-01 Sea-Tac Airport (SEA) – Water System Plan (Limited Update) Final Determination of Non-Significance Sea-Tac Airport
2025-01 Sea-Tac Airport (SEA) – Water System Plan (Limited Update) Environmental Checklist Sea-Tac Airport
2025-01 Sea-Tac Airport (SEA) – Water System Plan (Limited Update) Threshold Determination of Non-Significance Sea-Tac Airport
South Concourse Threshold Determination of Non-Significance Sea-Tac Airport
South Concourse Threshold Determination of Non-Significance Sea-Tac Airport
S Concourse Evolution Checklist Sea-Tac Airport
2024-02 T46 Substation No. 1 Replacement - SEPA Final Determination of Non-significance Maritime
2024-02 T46 Substation No. 1 Replacement - SEPA Checklist Maritime
2024-01 Sea-Tac Airport (SEA) – Aquatic Mosquito Control Program Final Determination of Non-Significance Sea-Tac Airport
2024-01 Sea-Tac Airport (SEA) – Aquatic Mosquito Control Program Threshold Determination of Non-Significance Sea-Tac Airport
2024-01 Sea-Tac Airport (SEA) – Aquatic Mosquito Control Program Environmental Checklist Sea-Tac Airport
2023-02 Sea-Tac Airport (SEA) – PCS Facility Improvements Final Determination of Non-Significance Sea-Tac Airport
2023-02 Sea-Tac Airport (SEA) – PCS Facility Improvements Threshold Determination of Non-Significance Sea-Tac Airport
2023-02 Sea-Tac Airport (SEA) – PCS Facility Improvements Environmental Checklist Sea-Tac Airport
2023-01 Terminal 91 Uplands Redevelopment Final Determination of Non-significance (Final DNS) Maritime
2023-01 Terminal 91 Uplands Redevelopment Environmental Checklist Maritime
2022-02 Sea-Tac Airport (SEA) — Tyee Pond Pipe Replacement: Final Determination of Non-Significance Sea-Tac Airport
2022-01 Sea-Tac Airport (SEA) – Snow Storage Expansion: Modified Final Mitigated Determination of Non-Significance Sea-Tac Airport
2022-02 Sea-Tac Airport (SEA) — Tyee Pond Pipe Replacement Environmental Checklist Sea-Tac Airport
2022-02 Sea-Tac Airport (SEA) — Tyee Pond Pipe Replacement Threshold Determination of Non-Significance (DNS) Sea-Tac Airport
2022-01 Sea-Tac Airport (SEA) Snow Storage Expansion: Final Mitigated Determination of Non-Significance Sea-Tac Airport
2022-01 Sea-Tac Airport (SEA) – Snow Storage Expansion: Environmental Checklist Sea-Tac Airport
2021-09 Harbor Island Marina Dock E Floats and North Pier Improvements FINAL DNS Maritime
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