Skaggs Island evolved from a tidal marsh beside San Pablo Bay, long used by Native Americans and important to migratory birds along the Pacific Flyway, into diked wetlands, hay farms, and salt ponds after nineteenth-century development reshaped California wetlands. The Navy bought the 3,310-acre site in 1941 and operated it from 1942 to 1993 as a secretive communications and intelligence station, including Cold War direction-finding work for the Navy and other federal agencies. After closure, its antennas lingered for a time, but by 2013 the buildings and towers were gone. Since March 31, 2011, the site has formed part of the San Pablo Bay National Wildlife Refuge as protected marsh habitat.