The refuge was established in 1937 and is the largest coastal marsh refuge on the Gulf. A primary management objective is to preserve a large area of coastal wetlands for wintering and migrating waterfowl from both the Mississippi and Central Flyways. It is also a major nursery area for many estuarine-dependent marine species as well as being home for the alligators and other reptiles, mammals, and numerous wading, water, and marsh birds.

The refuge contains 124,511 acres; its marshes range in salinities from fresh water to almost sea-strength.