The Delaware Reserve encompasses over 6,000 acres from the freshwater wetlands, ponds and forest lands of the Blackbird Creek Reserve to the salt marsh, mudflats, tidal creeks and open water habitats of the St Jones Reserve and Delaware Bay. The Delaware Bay provides habitat for many species of waterfowl, finfish, as well as clams, oysters and crabs. It has the second largest concentration of migrating shorebirds in the Western Hemisphere and the largest population of spawning horseshoe crabs in the world. The Delaware Reserve promotes the stewardship of estuarine and coastal areas through research and education.

The St. Jones Reserve component is located six miles southeast of Dover. The Blackbird Creek component is located in southern New Castle County.