Powder House Island is contained within Grosse Ile Township, in Wayne County, Michigan. It is near the southern end of the Detroit River, closer to Lake Erie than to Lake St. Clair, and around from the water border with Canada. It is approximately east of Fox Island. Further to its west is Grosse Ile, beyond which is Trenton. To its east, across the Livingstone Channel, is the Canadian Bois Blanc Island (and further, Amherstburg in Ontario). The southern tip of Stony Island is around to the northeast; other islands in the vicinity include Sugar Island to the south and Elba Island to the southwest. The island, which is covered in foliage, is approximately from north to south, and from east to west, giving it an approximate area of . The United States Geological Survey (USGS) gave its elevation as above sea level in 1980. In Wayne County records, the island is listed as "Dynamite Island", in ZIP code 48138; it is contained within a single parcel (whose total area is given as ).
