The Port of Seattle is dedicated to environmental stewardship. As one of the largest waterfront land owners in the Seattle area and around Seattle-Tacoma International Airport (SEA), we remain committed to protecting our waters.
Stormwater is the flow of water generated by precipitation and runoff from land, including pavement, building rooftops, and other hard surfaces. Hard or 'impervious surfaces' do not allow rainfall to absorb into the ground or filter through the soil. Runoff from hard surfaces may carry pollutants such as oil, grease, metals, and bacteria.
The Port’s Stormwater Management Programs strive to manage stormwater in a manner that improves the quality of the receiving waterbodies and ecosystems through best management practices, such as pollution reduction, and site-specific treatment and flow controls. The Port operates under various state stormwater permits and local regulations. Stormwater information is divided into Aviation and Maritime programs due to differences in permitting and the nature of activities that occur at the facilities.
Maritime Stormwater Program
The Port’s Maritime Stormwater Program operates under Washington State Department of Ecology (Ecology) stormwater permits and follows City of Seattle stormwater codes to help improve water quality discharges to state waters, including Elliot Bay, the Duwamish River and Salmon Bay. The Port works closely with state and local agencies, the Northwest Seaport Alliance, and our tenants to minimize the impact of stormwater runoff on local waters and aquatic habitats. Annually, the Maritime Port manages approximately 1.2 billion gallons of stormwater runoff from over 1,000 acres of facilities.
Aviation Stormwater Program
Clean water is a priority for businesses and citizens in Seattle and surrounding communities. The importance of water quality encompasses agriculture, commerce, tourism, recreation, and wildlife, all key drivers of the regional economy. Water quality is influenced by stormwater runoff and management. SEA Airport is responsible for 1,600 aces of drainage area that flows directly into three local streams and the Puget Sound.
Water Conservation at the Airport
Water conservation remains an important goal at SEA. In 2024, more than 52.6 million total passengers traveled through SEA. Since 2005, potable water use at the airport has been reduced by 18%, or almost 52 million gallons per year, through several programs such as restroom fixture upgrades and use of drought-resistant landscaping.
One inch of rain equals 20 million gallons of runoff!
