The Port of Seattle submitted an environmental checklist in January 2025 for a limited update to Seattle-Tacoma International Airport's Water System Plan, covering the period 2025–2028. The update addresses routine maintenance and infrastructure improvements to SEA's drinking water and fire protection system, including pipe replacements, new surge tanks, additional water storage, and a backup water supply connection to Highline Water District. Washington State Department of Health approval and Port of Seattle Commission adoption are required before the plan can be implemented.Open full document
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This SEPA environmental checklist reviews the potential environmental impacts of Port of Seattle adoption and Washington State Department of Health approval of the SEA Water System Plan Limited Update. The plan covers the 2025-2028 period and includes 16 recommended capital improvement projects to enhance reliability, redundancy, and flow capacity of the airport’s water system. A full update was deemed unnecessary as the 2008 Water System Plan remains essentially current.