The headwaters of Belt Creek arise in the heart of the Little Belt Mountains north of Kings Hill. The creek flows in a northerly course for nearly 81 miles before its confluence with the Missouri River 2 miles downstream of Morony Dam. The upper 33 miles of Belt Creek flow through a V-shaped mountain canyon. Running northwesterly from the Dry Fork Belt Creek at Monarch, Montana, for 15 miles the stream is mostly entrenched in a rugged gorge lined with limestone cliffs. The river emerges from the timbered canyon into a relatively narrow foothills valley. Belt Creek is paralleled for most of its length by paved highway. Willow, cottonwood, chokecherry, and wild roses grow along it in scattered spots in the canyon and in a continuous band up to 1/4 mile wide in the foothill zone. Aquatic habitat conditions are somewhat unstable in Belt Creek due to historical road and railroad construction, agriculture, mining, and other land-use activities.