The river begins in Klamath County in the Sky Lakes Wilderness of the Cascade Range. It flows north from Horseshoe Lake for about before turning northeast and entering Jackson County, leaving the wilderness area and entering the Rogue River–Siskiyou National Forest. Over its next, the river flows under Forest Road 37 at Upper South Fork Bridge, passes Upper South Fork Campground and receives Parker Creek from the near Parker Meadows Campground, then Little Billie, Wickiup, and Sam creeks from the. Below this, it receives Big Ben Creek from the right. The river then flows under Lower South Fork Bridge, which carries Forest Road 37, and by South Fork Campground, which is on the left. Below the bridge, the river receives Nichols and Green creeks from the right and Lodgepole Creek from the left. Imnaha Creek enters from the right at about river mile 10.5 or river kilometer 16.9 just above the South Fork diversion dam. Turning west below the dam, the South Fork flows by a United States Geological Surveystream gauge, which is on the left at RM 10.2. Buck Creek enters from the left about from the mouth, and the Middle Fork Rogue River enters from the right shortly thereafter. About further downstream, Beaver Dam Creek enters from the left, and Smith Creek enters from the left about later. The South Fork meets the Rogue River main stem near the head of Lost Creek Lake and about from the larger river's mouth on the Pacific Ocean.
Recreation
The river, lightly fished on its upper reaches, supports wild rainbow, coastal cutthroat, and brook trout. Campgrounds near or along the river include those at Joseph H. Stewart State Recreation Area, Imnaha, South Fork, Parker Meadows, and Upper South Fork. Hiking trails include Upper South Fork Trail 986, a primitive trail through South Fork Canyon near the headwaters to near Upper South Fork Bridge and Forest Road 37; Middle South Fork Trail, an easy trail between the upper and lower South Fork bridges, and Lower South Fork Trail, an easy trail between Lower South Fork Bridge and Imnaha Creek. Whitewater boating of the highest difficulty, Class 5, is possible at times on the Middle Fork Rogue River and on the South Fork below its confluence with the Middle Fork. The gorge through which this part of the Middle and South forks flow is sometimes impassable because of log jams. The entire run, including the gorge, requires scouting and expert ability, and "is no place for the faint of heart or the claustrophobic". Below the gorge, the South Fork is class 3 to the mouth.
