Rush River Delta protects a floodplain forest on the alluvial plain at the mouth of the Rush River where it empties into the Mississippi River's Lake Pepin. The area supports stands of lowland hardwoods including silver maple, cottonwood, willow, American elm, and green ash. Large patches of wood nettle dominate the groundlayer. Several open, wet depressions are vegetated with river bulrush and smartweed and provide excellent spawning habitat for northern pike and rearing areas for mallards and wood ducks. A sand spit extends into Lake Pepin at the Rush River mouth and provides nesting habitat for turtles and feeding and nesting areas for shorebirds. The surrounding woods supports many rare breeding birds including red-shouldered hawk (Buteo lineatus), Acadian flycatcher (Empidonax virescens), and cerulean warbler (Dendroica cerulea), prothonotary warbler (Protonotaria citrea), and contains a small great blue heron (Ardea herodias) rookery. Other woodland birds include yellow-throated vireo, warbling vireo, blue-gray gnatcatcher, American redstart, and northern oriole. Rush River Delta is owned by the DNR and was designated a State Natural Area in 1986.