The plant life in the park reflects the overlap of southern and northern ecosystems. Typically southern species, such as buffalo nut and Frazier's magnolia, are intermingled with northern species, such as striped maple and hemlock. Other dominant species are rhododendron, red maple, tulip tree, oak and hickory. Stream banks are lined with sweet birch and alders.

Along the Guyandotte River, which runs through Wyoming County just a few miles south of Twin Falls, archeologists have found a group of some 25 Indian petroglyphs or rock writings. These inscriptions provide the earliest evidence of man's existence in the area. The Indians are believed to have used the area along the river as hunting grounds. However, its ruggedness made travel so difficult that few, if any, settlements existed along the river. At least four different tribes-the Mingo, Shawnee, Cherokee and Wyoming-are ruputed to have used the area.

White settlement in the area that eventually became Twin Falls State Park began in the mid-1800s.