Freshwater Impoundments

Habitat Type

Management Unit 3, which encompasses 26,400 acres, is the largest freshwater marsh in southwest Louisiana. Management units 1A and 1B comprise 5,138 acres and 1,800 acres respectively, and are utilized by a variety of wildlife, most notably ducks.  Since hurricanes Rita and Ike in 2005 and 2008, respectively, these impoundments have been recovering from salt water inundation and further levee degradation.  

These impoundments have changed throughout their 57-65 years in existence.  Soils have built up from dead and decaying vegetation filling in some areas and ultimately changing plant communities.  Degraded levees weakened by tree roots, burrowing wildlife, and hurricane damage no longer prevent water exchange from surrounding waterways and marshes.  Saline water has caused large areas of plant die-offs creating large open lakes, which when impacted by wave action become turbulent and devoid of vegetation.  

The water control structures on the northwest and east sides of Unit 3 have been permanently opened to share water flow with adjacent canals to help dilute the saline water left behind by the hurricanes. The southern structure blocked by mud and vegetative debris since 2005, has been slowly reopening as vegetation decays and water flow moves mud.

Large open lakes in Unit 1A have been pumped with dredge material in recent years to restore marshes lost to salt water intrusion.  This Unit is no longer managed as freshwater impoundment; instead it is being restored to tidal marsh.   Unit 1B is where the ever popular 1.5 mile Wetland Walkway has resided since the mid-eighties.   Life long trail goers have witnessed the vegetative changes to climax plant communities of dense stands of bullwhip and cattails in the wetlands and Roseau cane on elevated areas.   

Facts About Freshwater Impoundments

Three rain-fed freshwater impoundments created in 1951 and 1959 provide habitat for numerous species of waterfowl, wading birds, shorebirds, mammals, reptiles and fish.