Marsh Island, formed between 5,000 and 7,500 years ago as part of the Mississippi River Delta, consists of approximately 71,000 acres of brackish and intermediate marsh and flat land located between Vermilion Bay, West Côte Blanche Bay, East Côte Blanche Bay and the Gulf of Mexico.

When purchased by Olivia Sage, the widow of railroad and financial magnate and philanthropist Russell Sage, the island was significantly larger at 76,664acres. Sage purchased the land through the Russell Sage Foundation in 1912 at the request of Louisiana businessman and conservationist Edward McIlhenny and fellow conservationist Charles Willis Ward with the intent of turning it over to the state of Louisiana as a wildlife refuge. She did so in 1920, and the island became the Marsh Island Wildlife Refuge.

The island’s loss of more than 5,000 acres over the past century has been attributed to erosion and hurricane damage and includes the conversion of substantial areas of interior emergent marsh to open water, creating significant habitat loss for animals as well as a loss of storm surge protection for the people of both Iberia and Vermilion parishes.

Serving as an important wintering ground for blue and snow geese, Marsh Island Wildlife Refuge is home to a wide variety of resident animals, including other waterfowl and wading and shore birds, birds of prey such as bald eagles, alligators, furbearers, fish, crab, and shrimp. The waters in and around the island are a popular destination for Louisianians and tourists interested in birding and recreational fishing, shrimping, and crabbing. Beyond the refuge’s perimeter in Vermilion Bay, commercial fisherman base their livelihoods on harvests of shrimp and blue crab that are dependent upon Marsh Island’s nursery habitats.

The island is also home to important research ranging from alligator population dynamics and fisheries to brackish marsh ecology, soil salinity, effects of water management techniques, and water quality monitoring by both the Louisiana Department of Wildlife and Fisheries (LDWF), which manages Marsh Island on behalf of the state, and universities.

LDWF has been working to improve the island’s wildlife habitat through water level management and maintenance units and through projects that have encompassed marsh creation and nourishment, shoreline protection, and terrace construction.