Southern Lake Union once extended to what is today Mercer Street. Industry’s waste filled in the lakeshore over time, including the byproducts of a coal landing, sawmill, garbage incinerator, and asphalt plant. The first industry to begin filling the lakeshore was the Western Mill steam sawmill built in 1880 by one of Seattle’s founders, David Denny. The mill gradually filled its pier with yard scrap creating the small peninsula where the Naval Reserve Base stands. The base operated from July 4, 1941 to July 4, 2000, when the Navy turned over the property to the City of Seattle and it became a park.