Decatur Island is one of the San Juan Islands in Washington state, USA, located just east of Lopez Island across Lopez Sound and just south of Blakely Island across Thatcher Pass. Named by the Wilkes Expedition in 1841 for naval officer Stephen Decatur, it is 3.524 square miles (9.127 km²) in area.
There is no Washington State Ferries service to Decatur; access is by private boat or plane. The airport on Decatur Island is private, for residents of the Decatur Shores community only. All other persons wishing to use the airport must obtain prior permission from the community. Paraclete Charter Service and Island Express Charters provide passenger-only ferry service to Decatur from Anacortes. Northwest Sky Ferry provides air service from Bellingham, Washington. Island Transport operates a ferry/barge, transporting cargo and vehicles from Skyline Marina in Anacortes to the public boat ramp. There are no public facilities other than one public boat ramp on the north side of the island.
In addition to the three private communities on Decatur (Decatur Northwest, Decatur Shores, and Decatur Head Beach Association), there are about 50 full-time residents, a school for kindergarten through eighth grade, and nine hole rustic golf course. The golf course is private but welcomes all players, furnishing clubs and balls for your use. A donation is suggested to help defray operating costs. Memorial Day to Labor Day there is a Farmer's Market each Saturday on the school grounds. The 2000 census, however, reported a resident population of 71 persons.
James Island State Park is just to the east of the island.
- Decatur Island: Blocks 2102 thru 2118, Census Tract 9605, San Juan County, Washington United States Census Bureau