The main stream flows approximately 150 miles before it is backed up by the dam at Possum Kingdom Reservoir. The upper reaches of the main stream do not normally have sufficient water for recreational use until the Clear Fork adds its flow in Young County. Therefore, only the small section (approximately 25 miles) between the confluence with the Clear Fork and the back-up waters from Possum Kingdom Reservoir generally has sufficient water for recreational purposes. The upper reaches of the main stream pass through semi-arid farming and ranching country. Here, the river meanders within its own streambed, depositing large sand bars between the steep banks.