Situated on the delta and extreme lower floodplain of the Trinity River, Wallisville Lake would destroy a rare and unique wetland complex ranging from cypress swamp to brackish marsh. The Texas Parks and Wildlife Department has referred to the Wallisville Lake area as the most prominent remaining deltaic ecosystem on the Texas coast. The area is unique in that is a relatively undisturbed ecosystem showing the ecological gradation of a river community from bottomland hardwood forest to estuarine marsh.