It had originally been established in 1934 as a secondary dredged material disposal site for use by the Army Corps of Engineers.

[2] Its status as a refuge was revoked in 1998 by the U.S. Congress and it is currently used as a confined disposal facility by the U.S. Army Corps of Engineers.

As outlined by the Twelve-Mile Circle, a colonial-era agreement, Killcohook is one place in Delaware that shares a land border with New Jersey, called Finn's Point.

Since the border was originally defined as being along the low-water mark on the New Jersey shore of the river, the reclaimed land on which the refuge lies falls within Delaware territory.

The former wildlife refuge is north of the Fort Mott State Park and south of Pennsville, New Jersey.