Big Branch Marsh National Wildlife Refuge (NWR) was established in October 1994, and is comprised of 15,000 acres of coastal marsh and pine forested wetlands. Of this total, the Conservation Fund has donated over 10,000 acres to the Service from Richard King Mellon Foundation funds.

The purpose of the refuge is to protect some of the only Lake Pontchartrain shoreline that exists in its natural state and to provide habitat for a diversity of wildlife species, with special emphases on migratory birds and endangered species.

The refuge supports over 5,000 wintering waterfowl, including mallards, gadwall and Northern Pintails. The endangered red-cockaded woodpecker and American bald eagle nest in the refuge's pine forests.

Public use opportunities include hunting, fishing, environmental education, and interpretive tours.