Edward McIlhenny and wealthy birdwatcher/conservationist Charles Willis Ward reached out to Russell Sage's widow, Margaret Olivia Slocum Sage, and through the Russell Sage Foundation she purchased the then 76,664 acres (31,025 ha) Marsh Island and turned it over to the LDWF in 1960.

[1] The island sits south of Cypremort Point State Park and north of the Gulf of Mexico.

Bayou Sale Bay is to the east with Burns Point Park at the end of La-317.

There is a restricted area on the southwest side between Lighthouse Point and Oyster Lake.

In the middle of this is Grosse Isle Point and Cheniere La Croix.