The state of Washington Department of Ecology will issue a new industrial stormwater general permit (ISGP) in January 2025. The Port of Seattle Maritime Division has more than 1,000 acres of waterfront properties in Seattle on the Puget Sound, Elliott Bay, Duwamish River, and Lake Washington Ship Canal. The Port’s Marine Stormwater Utility is responsible for asset management involving 70 miles of stormwater lines and stormwater permit compliance that includes the Phase I municipal stormwater permit and one ISGP for a maintenance yard. The 2025 ISGP, by adding ‘material handling/storage’ as an industrial trigger for the transportation sector, may expand the footprint of the Port’s ISGP coverage from 2 acres to as much as 150 acres for Port activities, and another additional 100 acres for tenants and the Northwest Seaport Alliance, a marine cargo operating partnership between the Ports of Seattle and Tacoma. This talk will review ISGP changes in the 2015 and 2020 permits, and how the 2025 permit differs from and greatly expands obligations for the transportation sector, including ports. It will share details of legal challenges, approaches for permit compliance, cost implications, and effects on the larger transportation sector of a state heavily engaged in import and export activities.