[3] Starting southeast of Hampton in Deschutes County, the South Fork flows east from near Ram Lake (dry).

It passes under U.S. Route 20 at Hampton, then continues east and north for about 6 miles (10 km) before entering Crook County.

Shortly thereafter, east of Hampton Buttes, it receives Buck Creek from the right and then passes through Logan Reservoir.

[5][6] The South Fork Crooked River drains a sparsely populated basin of 1,530 square miles (4,000 km2).

About 75 percent of the basin is rangeland; the rest is a mixture of forests, pasture, and hay fields.