The reservoir and surrounding terrain are characterized by eroded, gently-rolling brushland crossed by silted stream valleys. The present location of Choke Canyon Dam is near the ancient Gulf shoreline of about 30 million years ago. Erosion of ancient sea-floor sediments and subsequent deposits of river silt eventually produced the present terrain. Paleo Indians crossed the Frio River Valley more than 10,000 years ago following game such as bison and mammoth. After the disappearance of large game, more than 8000 years ago, nomadic hunters and gatherers associated with the Archaic culture camped near the river making tools, building fires, and gathering food. Numerous Archaic sites have been recorded in the Choke Canyon area. The park was acquired in 1981 in a 50 year cooperative agreement among the Bureau of Reclamation, the City of Corpus Christi, and the Nueces River Authority.